Biomedical subjects

Rita A Kandel

Publications and source records attributed to Rita A Kandel.

At least 19 recordsLinked to original sources

PubMed2006

Nuclear morphometric features in benign breast tissue and risk of subsequent breast cancer.

Certain nuclear morphometric features measured in breast tumor tissue have been shown to predict the prognosis of breast cancer patients. However, the application of these features to predicting risk of breast cancer development has received little attention. We conducted a case-control study to evaluate nuclear morphometric features in benign breast tissue in association with subsequent breast cancer risk. The study was nested within a cohort of 4,888 women with a histopathologic diagnosis of benign breast disease (BBD) and involved 61 cases and 71 controls, amongst whom there were 53 matched case-control sets. Conditional logistic regression models were fitted to assess various measurements of nuclear size and nuclear shape factors in relation to subsequent breast cancer risk. In multivariate analysis, subsequent breast cancer risk was positively associated with a nuclear shape factor that takes the shortest nuclear axis and the longest nuclear axis into consideration simultaneously (highest quartile versus lowest 3 quartiles: odds ratio = 3.07, 95% confidence limits = 1.61, 5.84). In contrast, there was no alteration in subsequent breast cancer risk in association with nuclear size features and other shape factors. In conclusion, our study results suggest that the shape factor that takes both the shortest nuclear axis and the longest nuclear axis into consideration might be of value to predict subsequent development of breast cancer among women with BBD.

Adult↗

PubMed2006

Differential regulation of matrix degrading enzymes in a TNFalpha-induced model of nucleus pulposus tissue degeneration.

Intervertebral disc degeneration occurs commonly and is linked to persistent back pain and the development of disc herniation. The mechanisms responsible for tissue catabolism have not yet been fully elucidated. Previously we characterized an in vitro model of TNFalpha-induced nucleus pulposus degeneration, which demonstrates decreased expression of matrix macromolecules, increased expression of matrix degrading enzymes, and the activation of aggrecanase-mediated proteoglycan degradation [Seguin, C.A., Pilliar, R.M., Roughley, P.J., and Kandel, R.A. 2005. Tumor necrosis factor-alpha modulates matrix production and catabolism in nucleus pulposus tissue. Spine 30: 1940-1948]. This study explores the intracellular pathways activated during TNFalpha-induced matrix degradation. We demonstrate that in nucleus pulposus cells, the p38 and JNK pathways regulate induction of MMP-1 and -3; p38, JNK, and NF-kappaB regulate the induction of MMP-13; and ERK regulates the up-regulation of MT1-MMP mRNA in response to TNFalpha. Induction of ADAMTS-4 and -5 mRNA occurred downstream of NF-kappaB activation. Depletion of tissue proteoglycans was mediated by ERK and NF-kappaB-dependent "aggrecanase" activity, suggesting MT1-MMP and ADAMTS-4 and -5 as effectors of TNFalpha-induced tissue catabolism.

ADAM Proteins↗

PubMed2006

p53 Alterations and protein accumulation in benign breast tissue and breast cancer risk: a cohort study.

Disruption of p53 gene function seems to have a pivotal role in carcinogenesis. p53 gene changes occur before the development of breast cancer and therefore might influence breast cancer risk. We investigated the association between p53 protein accumulation and p53 mutations detected in benign breast tissue and risk of subsequent breast cancer. We conducted a case-control study nested within the cohort of 4,888 women in the Canadian National Breast Screening Study who were diagnosed with biopsy-confirmed benign breast disease during active follow-up. Cases were women with benign breast disease who subsequently developed breast cancer; five controls were matched to each case. p53 protein accumulation was assessed immunohistochemically using sections of paraffin-embedded benign breast tissue from 104 cases and 385 controls; for 82 of these cases and 327 of the controls, DNA was successfully extracted from the breast tissue for p53 gene analysis using PCR-single-strand conformation polymorphism/direct sequencing. p53 protein accumulation was associated with a 2-fold increase in risk of progression to breast cancer [adjusted odds ratio (OR), 2.16; 95% confidence interval (95% CI), 1.08-4.30], whereas p53 nucleotide changes overall were not associated with altered risk (adjusted OR, 1.22; 95% CI, 0.68-2.19); those with both p53 immunopositivity and a p53 nucleotide change had an OR (95% CI) of 3.20 (1.21-8.50). Nonpolymorphic intronic changes were associated with a 2.8-fold increase in risk (OR, 2.84; 95% CI, 1.09-7.41). The results of this study suggest that p53 protein accumulation and nonpolymorphic intronic changes in p53 are associated with increased risk of progression to breast cancer in women with benign breast disease.

Adult↗

PubMed2005

The surgical and functional outcome of limb-salvage surgery with vascular reconstruction for soft tissue sarcoma of the extremity.

BACKGROUND: This study compared the surgical, oncological, and functional outcomes of patients undergoing limb-salvage surgery for extremity soft tissue sarcoma with vascular resection and reconstruction with the outcomes of those undergoing limb-salvage without vascular reconstruction. METHODS: Nineteen patients were identified from a prospective soft-tissue sarcoma database who underwent vascular resection and reconstruction as part of their limb-salvage surgery and who were followed up for at least 1 year or until death. Each of these 19 patients was case-matched to 2 additional patients on the basis of tumor location, size, and depth; patient age; and timing of radiation. To compare functional outcome, a subset of patients was case-matched with additional criteria including wound-complication status, motor nerve sacrifice, similar preoperative function as determined by the Toronto Extremity Salvage Score, and no metastases at diagnosis or the 1-year follow-up. RESULTS: Patients in the vascular reconstruction group were more likely to require a muscle transfer (53% vs. 18%; P = .008), experience a wound complication (68% vs. 32%; P = .03), experience deep venous thrombosis (26% vs. 0; P = .003), experience significant limb edema (87% vs. 20%; P = .001), and ultimately require an amputation (16% vs. 3%; P = .07). Patients who underwent vascular reconstruction had only slightly lower Toronto Extremity Salvage Score scores 1 year after surgery (78.5 vs. 84.2; P = .35). There were no significant differences in local or systemic tumor relapse between the two groups. CONCLUSIONS: Vascular reconstruction is a feasible option in limb-salvage surgery for soft tissue sarcoma but is associated with an increased risk for postoperative complications, including amputation. Although function is not significantly worse after vascular reconstruction, the results are less predictable.

Adult↗

PubMed2005

Formation of a nucleus pulposus-cartilage endplate construct in vitro.

Intervertebral disc (IVD) degeneration is a common problem and treatment options for persistent symptomatic disease are limited. Tissue engineering is being explored for its ability to reconstitute the functional components of the IVD. The purpose of this study was to determine whether it was possible to form in vitro a triphasic construct consisting of nucleus pulposus (NP), cartilage endplate (CEP), and a porous calcium polyphosphate (CPP) bone substitute. Bovine articular chondrocytes were placed on the top surface of a porous CPP construct and allowed to form cartilage in vitro. Nucleus pulposus cells were then placed onto the in vitro-formed hyaline cartilage. At 24 h scanning electron microscopy demonstrated that the NP cells maintained their rounded morphology, similar to NP cells placed directly on porous CPP. At 8 weeks histological examination of the triphasic constructs by light microscopy showed that a continuous layer of NP tissue had formed and was fused to the underlying cartilage tissue, which itself was integrated with the porous CPP. The incorporation of the cartilage layer was beneficial to the construct by improving tissue attachment to the CPP, as demonstrated by increased peak load and increased energy required for failure during shear loading when compared to a biphasic construct composed of nucleus pulposus-bone substitute only. This study demonstrates that it is possible to generate a multi-component construct with the incorporation of a CEP-like layer resulting in improved bone substitute-to-IVD tissue interface characteristics.

Animals↗

PubMed2005

Tumor necrosis factor-alpha modulates matrix production and catabolism in nucleus pulposus tissue.

STUDY DESIGN: This study examines changes in the production of extracellular matrix molecules as well as the induction of tissue degradation in in vitro formed nucleus pulposus (NP) tissues following incubation with tumor necrosis factor (TNF)alpha. OBJECTIVE: To characterize the response of NP cells to TNF-alpha, a proinflammatory cytokine present in herniated NP tissues. SUMMARY OF BACKGROUND DATA: TNF-alpha is a proinflammatory cytokine expressed by NP cells of degenerate intervertebral discs. It is implicated in the pain associated with disc herniation, although its role in intervertebral disc degeneration remains poorly understood. METHODS: In vitro formed NP tissues were treated with TNF-alpha (up to 50 ng/mL) over 48 hours. Tissues were assessed for histologic appearance, proteoglycan and collagen contents, as well as proteoglycan and collagen synthesis. Reverse transcriptase polymerase chain reaction was used to determine the effect of TNF-alpha on NP cell gene expression. Proteoglycan degradation was assessed by immunoblot analysis. RESULTS: At doses of 1-5 ng/mL, TNF-alpha induced multiple cellular responses, including: decreased expression of both aggrecan and type II collagen genes; decreases in the accumulation and overall synthesis of aggrecan and collagen; increased expression of MMP-1, MMP-3, MMP-13, ADAM-TS4, and ADAM-TS5; and induction of ADAM-TS dependent proteoglycan degradation. Within 48 hours, these cellular responses resulted in NP tissue with only 25% of its original proteoglycan content. CONCLUSIONS: Because low levels of TNF-alpha, comparable to those present physiologically, induced NP tissue degradation, this suggests that TNF-alpha may contribute to the degenerative changes that occur in disc disease.

ADAM Proteins↗

PubMed2005

Histologic assessment of peritumoral edema in soft tissue sarcoma.

PURPOSE: To evaluate whether satellite tumor cells can be identified histologically in the tissues surrounding a soft tissue sarcoma and whether their presence correlates with increased T(2)-weighted signal intensity on MRI. METHODS AND MATERIALS: Fifteen patients with a high-grade extremity or truncal soft tissue sarcoma underwent preoperative MRI. The extent of high T(2)-weighted signal changes in the tissues surrounding tumor, thought to represent peritumoral edema/reactive changes, was determined. Twelve patients received i.v. gadolinium, and contrast enhancement was determined. All patients underwent surgical resection in the absence of preoperative chemotherapy or radiotherapy. The presence of tumor cells in the surrounding tissues was determined histologically in representative paraffin-embedded sections and correlated with the MRI findings. RESULTS: The extent of peritumoral T(2)-weighted MRI signal changes ranged from 0 to 7.1 cm (mean, 2.5 cm); contrast enhancement ranged from 0 to 5.3 cm (mean, 1.1 cm). Sarcoma cells were identified histologically in the tissues beyond the tumor in 10 of 15 cases. In 6 cases, tumor cells were located within 1 cm of the tumor margin, and in 4 cases, malignant cells were found at a distance >1 cm and up to a maximum of 4 cm. The location of tumor cells beyond the margin did not correlate with tumor size nor did it correlate with the location or extent of peritumoral changes. CONCLUSION: The ability to identify tumor cells beyond the margin of a soft tissue sarcoma has important implications in planning appropriate targets for treatment. This could influence the use of new radiotherapy technologies such as intensity-modulated radiotherapy that aim to minimize treatment volumes through conformal planning.

Adult↗

PubMed2004

Radiation response: an additional unique signature of myxoid liposarcoma.

PURPOSE: Historically, myxoid liposarcoma (MLS) has been reported to show a marked clinical response to radiotherapy (RT), but objective data to support that contention have been lacking. We performed a retrospective analysis of the response of a group of MLS tumors to preoperative RT using tumor dimensions calculated from pretreatment imaging and the subsequent surgical specimen obtained approximately 1 month after RT. METHODS AND MATERIALS: Data were abstracted from the Princess Margaret Hospital prospective database on a series of patients with MLS who had undergone preoperative RT between 1991 and 1999. A group of malignant fibrous histiocytoma (MFH) patients treated on the same protocol served as controls. Pretreatment and posttreatment three-dimensional measurements were obtained; comparison tumor volume measurements were estimated using the ellipsoid formula, and the analysis was also repeated using the maximal tumor dimension. Identical measurement procedures were used for the MLS (experimental) and MFH (control) cases. RESULTS: A total of 16 MLS tumor specimens were available for analysis, and 16 MFH cases were randomly chosen for comparison. The mean pretreatment and posttreatment volume of the MLS tumors was 415 and 199 cm(3), respectively (P = <0.0001). The mean pretreatment and posttreatment volume of the MFH tumors was 264 and 273 cm(3), respectively (p = 0.804). The proportional reduction in the median tumor volume was 59% and -7% for MLS and MFH tumors, respectively. Both the absolute and the proportional reduction in volume for MLS tumors vs. MFH tumors was statistically significant (p = 0.006 and p = 0.002, respectively). CONCLUSION: These results provide the first objective data to support the idea that MLS tumors show a statistically significant reduction in size when treated with RT and that this response is greater than that of MFH tumors given the same RT. These results may be relevant to the management of MLS with combined RT and surgery in difficult anatomic situations in which adequate surgical excision is not feasible. They also confirm another unique characteristic of this unusual subtype of soft tissue sarcoma.

Adult↗

PubMed2004

Carbonic anhydrase IX as a marker for poor prognosis in soft tissue sarcoma.

PURPOSE: Hypoxia is associated with malignant progression and poor outcome in several human tumors, including soft tissue sarcoma. Recent studies have suggested that carbonic anhydrase (CA) IX is an intrinsic marker of hypoxia, and that CA IX correlates with poor prognosis in several types of carcinoma. The aim of this study was to quantify the extent of CA IX expression and to investigate whether CA IX is a marker for poor prognosis in soft tissue sarcoma patients at high risk of developing metastasis. EXPERIMENTAL DESIGN: Archival paraffin-embedded blocks were retrieved from 47 patients with deep, large, high-grade soft tissue sarcoma. Sections from two separate and representative tumor areas were immunostained for CA IX, and the CA IX-positive area fraction was quantified by image analysis, excluding areas of normal stroma and necrosis that were identified from serial H&E-stained sections. Patients were then subject to survival analysis. RESULTS: CA IX-positive area fractions of viable tumor tissue varied significantly between tumors (range, 0-0.23; median, 0.004), with positive membranous CA IX staining in 66% (31 of 47) of the tumors. Patients with CA IX-positive tumors had a significantly lower disease-specific and overall survival than patients with CA IX-negative tumors (P = 0.033 and P = 0.044, respectively). CONCLUSIONS: These data suggest that CA IX, a potential intrinsic marker of hypoxia, predicts for poor prognosis in patients with deep, large, high-grade soft tissue sarcoma. Larger studies are required to determine whether CA IX has independent prognostic value in this group of tumors.

Adult↗

PubMed2004

Tissue engineered nucleus pulposus tissue formed on a porous calcium polyphosphate substrate.

STUDY DESIGN: This study describes the formation of nucleus pulposus tissue using a novel tissue engineering approach. OBJECTIVES: To determine if a construct composed of nucleus pulposus tissue on the surface of a calcium polyphosphate substrate could be formed in vitro with properties similar to native nucleus pulposus tissue. SUMMARY OF BACKGROUND DATA: There is no optimal treatment for the persistent pain associated with intervertebral disc degeneration. Disc replacement using artificial intervertebral discs has met with some success, and biologic transplantation is limited by the availability of donor tissues. METHODS: Nucleus pulposus cells were isolated from bovine caudal intervertebral discs. Cells were seeded at high density on the upper surface of a porous bone substitute material (calcium polyphosphate) and maintained up to 6 weeks in culture. In vitro formed tissue was compared to native nucleus pulposus for histologic appearance, biochemical composition (tissue cellularity, proteoglycan and collagen accumulation), and compressive mechanical properties. RESULTS: When maintained on the surface of a three-dimensional substrate, nucleus pulposus cells formed a continuous layer of tissue with a proteoglycan content equivalent to the native tissue. Although collagen accumulation attained only 26% than that of the native tissue, there was no difference in tissue stiffness, viscosity, or weight-bearing capacity of the in vitro formed tissue when compared with the native tissue. CONCLUSION: Nucleus pulposus-like tissue formed in vitro on the surface of a calcium polyphosphate substrate resembles the native tissue in terms of proteoglycan content and compressive mechanical properties. These studies are the first step toward developing a functional spinal unit in vitro.

Animals↗

PubMed2004

Evaluation of oligonucleotide arrays for sequencing of the p53 gene in DNA from formalin-fixed, paraffin-embedded breast cancer specimens.

BACKGROUND: Routine tissue processing has generated banks of paraffin-embedded tissue that could be used in retrospective cohort studies to study the molecular changes that occur during cancer development. The purpose of this study was to determine whether a p53 microarray could be used to sequence the p53 gene in DNA extracted from formalin-fixed, paraffin-embedded (FFPE) tissues. METHODS: DNA was extracted from 70 FFPE breast cancer tissue specimens. p53 was sequenced with an oligonucleotide microarray (p53 GeneChip; Affymetrix), and the results were compared with the results obtained from direct sequencing. RESULTS: DNA was extracted from 62 of 70 cases. We identified 26 mutations in 24 of the 62 cases by the p53 GeneChip. No polymorphisms were detected, and exon 4 could not be evaluated in 20 cases. There were 43 genetic alterations detected by direct sequencing in 35 of the 62 cases. These consisted of 26 polymorphisms and 17 mutations in exons or splice sites. Fifteen mutations were identified by both methods. Direct sequencing detected significantly more gene alterations (43 of 54) in DNA extracted from FFPE tissue than the p53 GeneChip (26 of 54; P = 0.018). However, if the changes in exon 4 were eliminated from this comparison, the p53 GeneChip detected 26 of 27 mutations compared with direct sequencing, which identified 16 of 27 mutations. (P = 0.016). CONCLUSIONS: A combination of oligonucleotide microarray and direct sequencing may be necessary to accurately identify p53 gene alterations in FFPE breast cancer. The p53 GeneChip cannot be used to detect exon 4 polymorphisms (codon 72) in FFPE breast cancer tissue.

Breast Neoplasms↗

PubMed2004

Chondrocytes attach to hyaline or calcified cartilage and bone.

OBJECTIVE: The initial attachment of transplanted chondrocytes to the surface of a cartilage defect is crucial for the success of chondrocyte transplantation. The purpose of this study was to investigate the early interaction of chondrocytes with the deep or calcified zones of cartilage or the subchondral bone, joint surfaces to which transplanted chondrocytes might have to attach in vivo. DESIGN: Freshly isolated (primary) or passaged (P1) chondrocytes were seeded on the top of bone plugs having either a surface composed of mid-deep zone hyaline cartilage or calcified cartilage or bone only. The percent of cells that attached, the role of integrins in cell attachment, and gene expression after placement of the cells on the different surfaces were determined. RESULTS: Both primary and passaged chondrocytes attached efficiently to all three surfaces (over 88% of seeded cells). The chondrocytes showed a punctate distribution of beta 1-integrin and vinculin, which in areas co-localized with actin, suggesting that the cells formed focal adhesions. The primary chondrocytes had a different shape, appearance of focal contacts, and actin distribution when compared to passaged cells and these did not appear to be influenced by the type of surface to which the cells attached. Blocking either beta 1-integrin or alpha v beta 5 integrin partially inhibited (between 27 to 48% and 26 to 37% respectively) attachment of both primary and passaged chondrocytes to all surfaces. Blocking alpha v beta 3 had no effect on adhesion. There was expression of type II collagen and aggrecan core protein mRNA by 2h. The different surfaces did not appear to affect the expression of these genes up to 24h although gene levels were lower in passaged cells. CONCLUSIONS: Chondrocytes, either freshly isolated or passaged, have the potential to adhere to the different joint surfaces that could be exposed in a cartilage defect. Understanding how chondrocytes adhere and interact with damaged joint surfaces may help identify methods to enhance the retention of transplanted cells in the defect site and cartilage tissue formation.

Actins↗

PubMed2004

Lymph node metastasis in soft tissue sarcoma in an extremity.

For patients with soft tissue sarcoma in an extremity, the outcome is thought to be poor if lymph node metastasis develops. The purpose of this study was to examine the impact of lymphatic involvement from soft tissue sarcoma on patient survival. Thirty-nine (3.7%) of 1066 patients who had surgery for soft tissue sarcoma in an extremity had lymph node metastases develop. Three (20%) of 15 patients with epithelioid sarcoma, four (19%) of 21 patients with rhabdomyosarcoma, two (11.1%) of 18 patients with clear cell sarcoma, and two (11.1%) of 18 patients with angiosarcoma had lymphatic involvement. Thirty patients who had resection of involved lymph nodes had an estimated 5-year survival of 57%, whereas nine patients treated without surgery all died within 30 months. An estimated 4-year survival of 71% for patients with isolated lymph node metastases was significantly better than 21% for patients with synchronous systemic and lymph node involvement. There was no difference in outcome for patients with isolated lymphatic involvement compared with patients with American Joint Committee on Cancer Stage III extremity sarcomas. These results suggest that long-term survival is possible after surgical resection of lymphatic metastases from soft tissue sarcoma. The American Joint Committee on Cancer should consider separating isolated nodal metastases from systemic involvement in patients with Stage IV sarcoma.

Adolescent↗

PubMed2003

The influence of anatomic location on outcome in patients with soft tissue sarcoma of the extremity.

BACKGROUND: The anatomic location of an extremity soft tissue sarcoma may influence the patient's presentation, management, and local and systemic recurrence rates. The objective of this study was to compare the presentation, management, and outcome of patients with soft tissue sarcomas of the upper extremity and the lower extremity. METHODS: Prospectively collected data from patients who underwent limb-sparing surgery for extremity soft tissue sarcoma between January, 1986 and April, 1997 were analyzed. Local recurrence free rates and metastasis free rates were calculated using the method of Kaplan and Meier. Univariate and multivariate analyses of potential predictive factors were evaluated with the log-rank test and the Cox proportional hazards model. RESULTS: Of 480 eligible patients, 48 patients (10.0%) had a local recurrence, and 131 patients (27.3%) developed distant metastasis. The median follow-up of survivors was 4.8 years (range, 0.1-12.9 years). Patients with upper extremity tumors had smaller lesions (6.0 cm vs. 9.3 cm; P < 0.001), more often underwent unplanned excision before referral (89 patients [64.0%] vs. 160 patients [46.9%]; P < 0.001), and less often received radiotherapy (98 patients [70.5%] vs. 289 patients [84.8%]; P < 0.001). The 5-year local recurrence free rate was 82% for patients with sarcomas of the upper extremity and 93% for patients with sarcomas of the lower extremity (P = 0.002). The 5-year metastasis free rate was 82% for patients with sarcomas of the upper extremity and 69% for patients with sarcomas of the lower extremity (P = 0.013). CONCLUSIONS: Local recurrence was more frequent in patients who had sarcomas of the upper extremity compared with patients who had sarcomas of the lower extremity. Factors that contributed to this difference included histologic type, the use of radiotherapy, and local anatomy. Metastasis was more frequent among patients with sarcomas of the lower extremity, because those tumors tended to be large and deeper compared with upper extremity tumors.

Adolescent↗

PubMed2003

Effect of radiation and cell implantation on wound healing in a rat model.

BACKGROUND AND OBJECTIVES: Having shown that intra-dermal injection of fibroblasts decreases the effect of radiation on healing of superficial wounds, we now test the effect of fibroblasts and syngeneic marrow stromal cells on irradiated deep and superficial wounds. METHODS: Wistar rats received bilateral buttock irradiation followed by partial excision of the gluteus muscle bilaterally. In Protocol 1, one irradiated wound was treated with 1.2 x 10(7) autologous cells injected intra-dermally. In Protocol 2, the experimental side was treated with a fibrin and autologous cell implant (1.2 x 10(7) cells). Twenty-one days later, wound mechanical characteristics were tested. In Protocol 3, the effect of pooled marrow stromal cells on healing of superficial irradiated wounds in Lewis rats was similarly tested. RESULTS: The fibrin-fibroblast implant (Protocol 2) had no effect on wound mechanics. Superficial injection of fibroblasts (Protocol 1) significantly improved wound breaking strength when compared to the control group (mean +/- SEM, breaking strength: treated 504.6 +/- 37.0 g vs. control 353.4 +/- 35.2 g, P = 0.005). The dermal injection of marrow stromal cells also resulted in marked increases in breaking strength (mean +/- SEM, breaking strength: treated 338.5 +/- 39.9 g vs. control 187.1 +/- 12.0 g, P < 0.01). In both Protocols 1 and 3, ultimate tensile strength and toughness were increased in the side receiving cell transplantation. CONCLUSIONS: Cell implantation holds promise for decreasing the effect of radiation on healing of irradiated wounds.

Animals↗

PubMed2003

The use of specific chondrocyte populations to modulate the properties of tissue-engineered cartilage.

Tissue engineering of articular cartilage is a promising alternative to the conventional approaches for cartilage repair. However, recent attempts to develop articular cartilage in vitro have proven to be difficult. The tissue formed in vitro may not accumulate enough extracellular matrix, and the resulting mechanical properties are only a fraction of the native tissue. We investigated whether using specific populations of chondrocytes would improve the properties of the cartilaginous tissue that was generated in vitro. Full-thickness (FT), mid-and-deep zone (MD), and deep-zone (DEEP) chondrocytes were isolated, placed on the surface of porous ceramic substrates and maintained in culture for eight weeks. Tissue developed from DEEP chondrocytes was thicker (FT: 0.94+/-0.03, MD: 0.88+/-0.04, DEEP: 2.4+/-0.1 mm) and had accumulated larger amounts of extracellular matrix (FT: 1.61+/-0.05, MD: 1.5+/-0.1, DEEP: 3.8+/-0.2 mg dry weight) than the tissues formed by the FT and MD chondrocytes. The tissue formed by the FT chondrocytes accumulated the greatest amount of collagen (FT: 211+/-14, MD: 185+/-8, DEEP: 178+/-5 microg/mg dry weight) whereas the tissue formed by the MD chondrocytes accumulated significantly more proteoglycans (FT: 198+/-10, MD: 265+/-10, DEEP: 215+/-5 microg/mg dry weight). Interestingly, MD chondrocytes produced tissue that had compressive mechanical properties up to four times greater than the cartilaginous tissues formed by cells from either the FT or DEEP of cartilage. Thus, a combined population of intermediate and DEEP chondrocytes might be more suitable for the tissue engineering of articular cartilage.

Animals↗

PubMed2003

Long-term intermittent shear deformation improves the quality of cartilaginous tissue formed in vitro.

The formation of cartilaginous tissue in vitro is a promising alternative to repair damaged articular cartilage. However, recent attempts to tissue-engineer articular cartilage that has similar properties to the native tissue have proven to be difficult. The in vitro-formed cartilaginous tissue typically has a similar proteoglycan content to native cartilage, but has a reduced collagen content and only a fraction of the mechanical properties. In this study, we investigated whether the intermittent application of cyclic shearing forces during tissue formation would improve the tissue quality. Chondrocyte cultures were stimulated at a 2% shear strain amplitude at a frequency of 1 Hz for 400 cycles every 2nd day. At one week, both collagen and proteoglycan synthesis increased (23+/-6% and 20+/-6%, respectively) over the unstimulated, static controls. At four weeks, an increased amount of tissue formed (stimulated: 1.85+/-0.08, unstimulated: 1.58+/-0.07 mg dry wt.). This tissue contained approximately 40% more collagen (stimulated: 511+/-23, unstimulated: 367+/-24 microg/construct) and 35% more proteoglycans (stimulated: 376+/-21, unstimulated: 279+/-26 microg/construct). Tissues that formed in the presence of shearing forces also displayed a 3-fold increase in compressive load-bearing capacity (stimulated: 16+/-5, unstimulated: 5+/-1 kPa max. equilibrium stress) and a 6-fold increase in stiffness (stimulated: 112+/-36, unstimulated: 20+/-6 kPa max. equilibrium modulus) compared to the static controls. These results demonstrate that intermittent application of dynamic shearing forces over a four-week period improves the quality of cartilaginous tissue formed in vitro. Interestingly, low amplitudes of shear stimulation for short periods of time (6 min of stimulation applied every 2nd day) produced these changes.

Animals↗

PubMed2003

Osseous invasion by soft-tissue sarcoma: assessment with MR imaging.

PURPOSE: To assess magnetic resonance (MR) imaging signs and overall accuracy of MR imaging for detection of osseous invasion by soft-tissue sarcoma, with histopathologic correlation as the reference standard. MATERIALS AND METHODS: Preoperative MR images (1.5 T, transverse and longitudinal planes, T1 and T2 weighted) of 56 osseous sites in 51 patients who underwent bone resection at surgery for soft-tissue sarcoma were assessed retrospectively for signs of osseous invasion, by consensus of two readers who were blinded to clinical and histopathologic findings. Delay between MR imaging and surgery averaged 34 days (range, 2-112 days). MR signs assessed included osseous abutment by tumor, maximal diameter of osseous abutment, extent of circumferential abutment of long bones (<25%, 25%-50%, >50%), cortical destruction, and cortical and medullary signal intensity change on T1- and T2-weighted images. Imaging findings were correlated with histopathologic findings. Sensitivities, specificities, positive and negative predictive values (PPV, NPV), and P values were calculated. RESULTS: Eleven sites (20%) showed osseous invasion histologically (two, cortical; nine, both cortical and medullary). Tumor abutted bone at 44 lesion sites (sensitivity, 100%; specificity, 27%). Maximal diameter of osseous abutment and extent of circumferential abutment did not significantly affect osseous invasion (P =.09 and.11, respectively). On T1- and T2-weighted images, 13 lesion sites showed cortical signal intensity change (sensitivity, 100%; specificity, 96%) and 10 showed cortical destruction (sensitivity, 82%; specificity, 98%). Eleven sites showed decreased medullary T1 signal intensity (sensitivity, 100%; specificity, 96%), and 12 showed increased medullary T2 signal intensity (sensitivity, 100%; specificity, 94%). MR imaging overall had a sensitivity of 100%, specificity of 93%, PPV of 79%, and NPV of 100% for detection of osseous invasion on the basis of any finding of cortical destruction or cortical or medullary signal intensity change on T1- or T2-weighted images (P <.001). CONCLUSION: On T1- and T2-weighted MR images, findings of cortical and medullary signal intensity change and cortical destruction were sensitive and specific for detection of osseous invasion by soft-tissue sarcoma.

Adolescent↗