Biomedical subjects

Irving M Shapiro

Publications and source records attributed to Irving M Shapiro.

36 records · Page 2Linked to original sources

PubMed2005

Intrauterine fetal constraint induces chondrocyte apoptosis and premature ossification of the cranial base.

BACKGROUND: The spheno-occipital synchondrosis is an important growth center of the craniofacial skeleton and a primary site of malformation in syndromic forms of craniosynostosis. Clinical and laboratory investigations have demonstrated that premature closure of cranial vault sutures in nonsyndromic craniosynostosis is associated with characteristic alterations in cranial base morphology. However, a causal link between premature fusion of calvarial sutures and changes in the cranial base remains elusive. The purpose of these experiments was to test the hypothesis that intrauterine head constraint produces ultrastructural changes in the spheno-occipital synchondroses of fetal mice. METHODS: Fetal constraint was induced through uterine cerclage of six pregnant C57Bl/6 mice on the eighteenth day of gestation. Fetuses were harvested after growing to 24, 48, and 72 hours beyond the normal 20-day gestational period. Between six and nine fetuses were harvested at all time points in both treatment and control groups. The morphology and cell biology of the spheno-occipital synchondroses, in constrained fetuses and unconstrained controls, were examined using hematoxylin and eosin-stained sections. Chondrocyte apoptosis was examined using terminal deoxynucleotidyl transferase-mediated dUDP end-labeling assays and electron microscopy. RESULTS: In nonconstrained animals, the spheno-occipital synchondrosis demonstrated normal architecture and normal chondrocyte morphology at all time points. In contrast, intrauterine constraint resulted in a progressive disruption of the normal cellular architecture of the spheno-occipital synchondrosis over 72 hours, with premature ossification of the synchondrosis. Widespread chondrocyte apoptosis within the synchondrosial growth center was demonstrated by terminal deoxynucleotidyl transferase-mediated dUDP end-labeling assays and electron microscopy. CONCLUSION: These experiments confirm the ability of intrauterine constraint to induce changes in the morphology and cell biology of the cranial base in synostotic fetuses.

Animals↗

PubMed2004

Fibronectin adsorption on surface-activated poly(dimethylsiloxane) and its effect on cellular function.

This article reports that surface modification of poly(dimethylsiloxane) (PDMS) influences fibronectin (Fn) adsorption and enhances cell attachment. Controlled adsorption of Fn on chemically activated polymer substrates is known to influence cellular function. Thin films of PDMS were spun cast on silicon wafers to obtain homogeneous and molecularly smooth surfaces. The films were made hydrophilic by exposure to ultraviolet ozone activation (PDMS*). The films then were characterized by contact angle goniometry, ellipsometry, atomic force microscopy (AFM), Rutherford backscattering spectrometry and X-ray photoelectron spectroscopy. Contact angle measurements indicated higher hydrophobicity of the nonactivated PDMS substrates than PDMS*. AFM scans of the substrates indicated higher surface roughness of PDMS* (Ra = 0.55 nm) than PDMS (Ra = 0.25 nm). Although Fn surface density (Gamma) was slightly higher on PDMS than on PDMS*, due to hydrophobic interactions between substrate and Fn, cell function was greatly enhanced on the Fn-coated PDMS* (PDMS*-Fn) than on PDMS (PDMS-Fn). Higher attachment of MC3T3-E1 osteoblast-like cells was observed on PDMS*-Fn than on PDMS-Fn. Moreover, cell spreading and cytoskeleton organization after 72 h was clearly favored on the Fn-coated PDMS* surfaces.

Actins↗

PubMed2004

Differentiation of mesenchymal stem cells towards a nucleus pulposus-like phenotype in vitro: implications for cell-based transplantation therapy.

OBJECTIVE: Because mesenchymal stem cells can differentiate into chondrocyte-like cells, we ask the question, can mesenchymal stem cells commit to the nucleus pulposus phenotype? BACKGROUND: Back pain, a significant source of morbidity in our society, is linked to degenerative changes of the intervertebral disc. Absence of suitable graft tissue limits therapeutic approaches for repair of disc tissue. For this reason, there is considerable interest in developing "tissue engineering" strategies for the regeneration of the nucleus pulposus. METHODS: Rat mesenchymal stem cells were immobilized in 3-dimensional alginate hydrogels and cultured in a medium containing transforming growth factor-beta1 under hypoxia (2% O2) and normoxia (20% O2). Mesenchymal stem cells were examined by confocal microscopy to evaluate their viability and metabolic status after labeling with Celltracker green, a thiol sensitive dye, and Mitotracker red, a dye sensitive to the mitochondrial membrane potential. Flow cytometry, semiquantitative reverse transcription polymerase chain reaction and Western blot analysis were carried out to evaluate phenotypic and biosynthetic activities and the signaling pathways involved in the differentiation process. RESULTS: Under hypoxic conditions, mesenchymal stem cells formed large aggregates and exhibited positive Celltracker and Mitotracker signals. Glucose transporter-3, matrix metalloproteinase-2, collagen type II and type XI, and aggrecan mRNA and protein expression was upregulated, whereas there was no change in the levels of decorin, biglycan, fibromodulin, and lumican. Hypoxia maintained the expression of CD44 (hyaluronan receptor), ALCAM (CD166), and endoglin (transforming growth factor-beta receptor). Likewise, expression of beta3 and alpha2 integrin was upregulated. Transforming growth factor-beta treatment increased MAPK activity and Sox-9, aggrecan, and collagen type II gene expression. Basal levels of the phosphorylated MAPK isoform ERK1/2, but not p38, were higher under hypoxic conditions than normoxia, and its activation was further augmented by treatment of cells with transforming growth factor-beta. In hypoxia, transforming growth factor-beta sustained phosphorylated p38 expression for an extended time period. Pharmacological inhibition of ERK1/2 and p38 enzymatic activity resulted in a decrease in Sox-9, aggrecan, and collagen type II mRNA levels. CONCLUSIONS: Our results indicate that hypoxia and transforming growth factor-beta drive mesenchymal stem cell differentiation towards a phenotype consistent with that of the nucleus pulposus. Measurement of selected signaling molecules and response to specific inhibitors suggest involvement of MAPK signaling pathways. It is concluded that mesenchymal stem cells could be used to repopulate the damaged or degenerate intervertebral disc.

Animals↗

PubMed2004

Apoptosis and survival of osteoblast-like cells are regulated by surface attachment.

We tested the hypothesis that RGDS peptides regulate osteoblast survival in culture. Osteoblast-like MC3T3-E1 cells were allowed to attach to RGDS peptides that had been tethered to a silicone surface utilizing a previously described grafting technique. The RGDS-modified surface caused up-regulation of alpha(v)beta(3) integrin. We noted that there was an increase in expression of activated focal adhesion kinase and activated Akt. There was no change in the expression level of the anti-apoptotic protein Bcl-2, the pro-apoptotic protein Bad, or the inactivated form of Bad, pBad. Attachment to the RGDS-treated membrane completely abolished apoptosis induced by staurosporine, the Ca(2+).P(i) ion pair, and sodium nitroprusside. However, the surface modification did not interfere with apoptosis mediated by the free RGDS peptide or serum-free medium. When the activity of the phosphatidylinositol 3-kinase pathway was inhibited, RGDS-dependent resistance to apoptosis was eliminated. These results indicated that the binding of cells to RGDS abrogated apoptosis via the mitochondrial pathway and that the suppression of apoptosis was dependent on the activity of phosphatidylinositol 3-kinase.

3T3 Cells↗

PubMed2004

Decellularized vein as a potential scaffold for vascular tissue engineering.

PURPOSE: Current strategies to create small-diameter vascular grafts involve seeding biocompatible, compliant scaffolds with autologous vascular cells. Our purpose was to study the composition and strength of decellularized vein to determine its potential as a vascular tissue-engineering scaffold. METHODS: Intact human greater saphenous vein specimens were decellularized by using sodium dodecyl sulfate (SDS). Residual cellular and extracellular matrix composition was studied with light and electron microscopy as well as immunohistochemistry. Burst and suture-holding strength was measured in vitro by insufflation and pull-through techniques. To assess initial handling and durability of decellularized vein in vivo, a canine model was developed wherein decellularized canine jugular veins were implanted as carotid interposition grafts in recipient animals. After two weeks of arterial perfusion, these grafts were studied with duplex imaging and histologic methods. RESULTS: Human saphenous vein decellularized by using SDS was devoid of endothelial cells and >94% of the cells resident within the vein wall. Collagen morphology appeared unchanged, and elastin staining decreased only slightly. Basement membrane collagen type IV remained intact. Compared with fresh vein, decellularized vein had similar in vitro burst (2480 +/- 460 mm Hg vs 2380 +/- 620 mm Hg; P >.05) and suture-holding (185 +/- 30 gm vs 178 +/- 66 gm; P >.05) strength. Decellularized canine vein functioned well in vivo without dilation, anastomotic complication, or rupture over 2 weeks of arterial perfusion. CONCLUSIONS: Vein rendered acellular with SDS has well-preserved extracellular matrix, basement membrane structure, and strength sufficient for vascular grafting. These properties suggest proof of concept for its use as a scaffold for further vascular tissue engineering. CLINICAL RELEVANCE: The following research examines the creation of a new small-diameter bypass graft. It is clinically relevant to patients who need distal arterial bypass, coronary artery bypass, or hemodialysis access, but who do not have adequate autologous vein for their surgeries. Future investigations will involve further tissue engineering of this vascular scaffold (eg, autologous endothelial seeding of its lumen) and testing the clinical usefulness of the completed graft.

Antigens, Surface↗

PubMed2004

Frank Stinchfield Award. Titanium surface with biologic activity against infection.

Despite immense improvements, periprosthetic infection continues to compromise the result of otherwise successful joint arthroplasty. There are various limitations in the treatment of periprosthetic infection, the most important of which is the inability to deliver antibiotics to the local tissue without the need for intravenous administration. We have developed a novel route to covalently tether vancomycin to a metal (titanium) surface, which showed effective bactericidal activity because of a vancomycin coupling. The chemistry of tethering does not affect the biological activity of the biofactors that are attached to the metal surface. This technology holds great promise for the manufacturing of "smart" implants that can be self protective against periprosthetic infection, or can be used for the treatment of periprosthetic infections when they occur.

Awards and Prizes↗

PubMed2004

Modeling of phosphate ion transfer to the surface of osteoblasts under normal gravity and simulated microgravity conditions.

We have modeled the transport and accumulation of phosphate ions at the remodeling site of a trabecular bone consisting of osteoclasts and osteoblasts situated adjacent to each other in straining flows. Two such flows are considered; one corresponds to shear levels representative of trabecular bone conditions at normal gravity, the other corresponds to shear level that is representative of microgravity conditions. The latter is evaluated indirectly using a simulated microgravity environment prevailing in a rotating wall vessel bioreactor (RWV) designed by NASA. By solving the hydrodynamic equations governing the particle motion in a RWV using a direct numerical simulation (DNS) technique, the shear stress values on the surface of the microcarriers are found. In our present species transfer model, osteoclasts release phosphate ions (Pi) among other ions at bone resorption sites. Some of the ions so released are absorbed by the osteoblast, some accumulate at the osteoblast surface, and the remainder are advected away. The consumption of Pi by osteoblasts is assumed to follow Michaelis-Menten (MM) kinetics aided by a NaPi cotransporter system. MM kinetics views the NaPi cotransporter as a system for transporting extracellular Pi into the osteoblast. Our results show, for the conditions investigated here, the net accumulation of phosphate ions at the osteoblast surface under simulated microgravity conditions is higher by as much as a factor of three. Such increased accumulation may lead to enhanced apoptosis and may help explain the increased bone loss observed under microgravity conditions.

Animals↗

PubMed2003

An organ culture system for the study of the nucleus pulposus: description of the system and evaluation of the cells.

STUDY DESIGN: The goal of this study was to develop a methodology to maintain intervertebral discs in organ culture, thereby preserving tissue architecture and metabolic function in a three-dimensional environment. METHODS: Using a microdissection technique, intervertebral discs were removed from rat lumbar vertebrae. The discs were maintained in organ culture, and cell viability was evaluated histochemically and using probes that measured mitochondrial function and thiol status. The biosynthetic activity of the cells was evaluated by Western blot and RT-PCR analysis. RESULTS: The in vitro organ culture system maintained the vitality of the nucleus pulposus cells. Cells exhibited a high membrane potential for 1 week. When cells were exposed to carbonyl cyanide 4-trifluoromethoxy phenylhydrazone, a known protonophore, the fluorescence was lost, indicating that the staining was specific for viable cells. In many cells, Celltracker Green, probe for reduced thiols, colocalized with the membrane potential. Histologic studies revealed that in culture for 1 week, normal nucleus pulposus structure was maintained; after this time period, alterations were observed. We evaluated the two tissues for characteristic phenotypic markers HIF-1alpha and MMP-2. We noted that the nucleus pulposus expressed these proteins. The RT-PCR profile at 7 days indicated that the cells also expressed collagen type II, aggrecan, and decorin. DISCUSSION: Three factors contributed to success in maintaining the vitality of the nucleus pulposus in vitro. First, the cells were confined within the disc itself; second, the medium was hyperosmotic; third, the medium was supplemented with transforming growth factor-beta. The fluorescence measurement provided a rapid method for evaluation of the status of nucleus pulposus cells. Histologic analysis confirmed that the cells remained viable for at least 1 week. Viability in terms of biosynthetic activity was further confirmed using RT-PCR and Western blot analysis. We conclude that short-term intervertebral disc organ culture can be used as a suitable in vitro model to study effects of environmental factors linked to disc degeneration and/or regeneration.

Animals↗

PubMed2003

Detection of apoptotic gene expression in human osteoblast-like cells by cDNA microarrays.

Global gene expression during the induction of ion pair-mediated apoptosis was evaluated by an apoptosis microarray system. Human bone marrow stromal cells were cultured in the presence of 10(-6) M dexamethasone to promote osteogenesis. After 28 days, these cells expressed elevated alkaline phosphatase activity and maintained Cbfa1 expression even when challenged with an apoptogen. Apoptosis was initiated by treating cells with 3 mM Ca(2+) and 5 mM Pi for 4 h. 32P-Labeled mRNA was hybridized to a human apoptosis microarray containing 205 cDNA fragments. We found that apoptosis influenced the expression of 15 genes mainly involved in cell cycle and cell signaling. These genes included IGFBPs and ERK1, known to play a role in cell survival; GST and GST mu, required for maintenance of thiol redox; TNFR1, a gene product that initiates cell death; and finally, BAD, a gene that encodes a proapoptotic protein. Real-time PCR analysis showed that the expression of ERK1, TNFR1, and GST was modulated by 1.89-, 2.66-, and 1.6 fold after 4 h and by 1-, 1.91-, and 1.5 fold, respectively, after 8 h treatment with the ion pair. In addition, we also measured the expression of Bcl-2 and Bax by quantitative RT-PCR. We noted that these two genes were increased 3.07 and 2.99 fold, respectively, after 8 h treatment with the apoptogen. Results of this study suggest that the ion pair influenced ERK1 and TNFR1 signaling pathways and affected thiol metabolism, whereas Bcl-2 and Bax were expressed at late stages of the death process.

Apoptosis↗

PubMed2003

Intervertebral disc tissue engineering I: characterization of the nucleus pulposus.

The characteristics of the nucleus pulposus cells from adult rabbits maintained in in vitro cultures were described in another study. Herein, the authors provide a parallel profile of adult rabbit nucleus pulposus in situ, therefore allowing direct comparisons between in vitro and in situ investigations. Nucleus pulposus specimens from adult rabbits were evaluated using biochemical and immunohistochemical morphologic techniques. The nucleus pulposus from adult rabbits contained cell clusters embedded in proteoglycan-collagen matrix. The cells exhibited a well-defined Golgi system, an extensive endoplasmic reticulum, and a complex vesicular system filled with beaded structures (proteoglycans). Neither necrotic nor apoptotic cells were evident. There was a lack of mitochondria. The extensive extracellular matrix contained amorphous, beaded, and fibrillar components. The fibrillar banding was indicative of Type VI collagen. The nucleus pulposus of adult rabbits expressed aggrecan, collagen Type I and Type II, and CD44, but not collagen Type X and displayed low alkaline phosphatase activity.

Animals↗

PubMed2003

Intervertebral disc tissue engineering II: cultures of nucleus pulposus cells.

The main objective of the current investigation was to regenerate cells of the nucleus pulposus without loss of phenotype. Nucleus pulposus cells were isolated from intervertebral discs from adult rabbits, grown in monolayer culture, and then maintained as a micromass pellet in tube culture. The specimens were evaluated by transmission and light microscopy, reverse transcriptase polymerase chain reaction, and immunohistochemistry. Nucleus pulposus cells proliferated in monolayer culture. When almost confluent, the cells were transferred to a tube and sedimented to form a pellet. The cells reverted to a rounded configuration and formed cell nests surrounded by extensive extracellular matrix, similar to that seen in vivo. These cells did not proliferate. Similar to that observed in situ, cells in pellet culture also expressed aggrecan, CD44, collagen Type II, and collagen Type I, but not collagen Type X, and had low alkaline phosphatase activity. The results of the investigation indicated that nucleus pulposus cells grown in monolayer culture might revert to their original characteristics when transferred to an environment that allows three-dimensional growth, such as upon implantation, a one-step approach. The results also indicated that the two-stage culture procedure might provide an expedient technique to regenerate nucleus pulposus tissue for disc repair.

Animals↗

PubMed2003

Maturation-dependent thiol loss increases chondrocyte susceptibility to apoptosis.

The major aim of the current investigation was to evaluate the role of thiols during chondrocyte maturation and apoptosis. Using a thiol-sensitive fluorescent probe, we found that in chick growth plate chondrocytes, hypertrophy is accompanied by a decrease in the glutathione content. In this study, we show that the maturation-dependent loss of thiol, although not causing death of maturing chondrocytes, drastically increases susceptibility to apoptosis by oxidative and nitrosoactive stress. To investigate how the loss of thiol content in cultured chondrocytes affects the expression of the hypertrophic phenotype, we chemically manipulated intracellular thiol levels and analyzed the expression of important maturation markers. We found that thiol depletion causes a decrease in the expression of osteopontin, type X and type II collagen and a significant loss of alkaline phosphatase activity, suggesting that the expression of the hypertrophic phenotype is tightly regulated by redox levels in chondrocytes. Furthermore, severe thiol depletion profoundly affected cell survival under oxidative and nitrosoactive stress. It was concluded that the loss of thiol reserve is not only linked to the expression of the hypertrophic phenotype but also influenced chondrocyte survival, linking chondrocyte maturation and the activation of the apoptotic pathway.

Acetylcysteine↗

PubMed2002

Phenotypic characteristics of the nucleus pulposus: expression of hypoxia inducing factor-1, glucose transporter-1 and MMP-2.

Attempts to study the biology of the nucleus pulposus have been limited in scope due to the low rates of cell proliferation, difficulties in maintaining viable disc cells in culture and the absence of a clearly defined phenotype. The major objective of this communication is to construct a phenotypic signature for cells of the nucleus pulposus that is based on the hypothesis that in response to restriction on oxygen and nutrient flux, there is expression of HIF-1, GLUT-1 and MMP-2. Nucleus pulposus, as well as annulus fibrosus and cartilage of the vertebral end plates, was collected from rat spinal units. Western blot analysis and immunohistochemistry clearly showed that there was a significant level of expression of the HIF-1 beta isoform in the nucleus pulposus; HIF-1 beta was present at lower levels in cells of the annulus and the end plate. In contrast to HIF-1 beta, HIF-1 alpha was expressed only in the nucleus pulposus. This isoform was absent from both the cartilage end plate and annulus. We detected HIF-1 alpha immunohistochemically in the nucleus pulposus; however, the staining was light and diffuse. Cells of the nucleus pulposus expressed GLUT-1; in contrast, when probed by Western blot analysis the annulus and cartilage were negative for this protein. Western blot analysis also showed that in the nucleus pulposus the level of MMP-2 was high when compared to the adjacent tissues. We suggest that the differential expression of the two HIF isoforms, and GLUT-1 and MMP-2, provides a phenotypic signature that permits cells of the nucleus pulposus to be distinguished from neighboring tissues. Moreover, the presence of these isoforms provides evidence that cells of the disc respond to hypoxia and nutrient stress by upregulating stress-responsive genes.

Animals↗

PubMed2002

Mercury-induced apoptosis in human lymphocytes: caspase activation is linked to redox status.

There is growing evidence that heavy metals, in general, and mercurial compounds, in particular, are toxic to the human immune system. We have previously shown that methyl mercuric chloride (MeHgCl) is a potent human T-cell apoptogen; moreover, mitochondria appear to be a target organelle for the induction of cell death. The objective of this study was to determine the impact of MeHgCl on mitochondrial function in lymphocytes in terms of modulating reactive oxygen species (ROS) generation, thiol status, and caspase activation. Using the fluorescent probe, 3,3'-dihexyloxacarbocyanine, we demonstrated that exposure to MeHgCl for 1 h resulted in a profound decrease in the mitochondrial transmembrane potential. We next observed the release of cytochrome c from mitochondria into the cytosol; significant translocation was noted between 4 and 8 h following treatment with mercury. ROS generation was monitored by following the conversion of dihydroethidium to the fluorescent product, ethidium. Kinetic analysis indicated that ROS generation was maximal after 16 h of exposure to MeHgCl. The toxicant also depleted the thiol reserves of the cell; glutathione levels were depleted in a dose-dependent fashion reaching minimal levels at 16 h. Real-time RT-PCR analysis demonstrated a significant reduction in both glutathione S-transferase and glutathione peroxidase gene expression in mercury-treated cells. Finally, after 16 h of treatment with MeHgCl, we observed activation of caspase-8, -9, and -3 along with increased expression of caspase-8 and -9. We propose that the target organelle for MeHgCl is the mitochondrion and that induction of oxidative stress is critical to activation of death-signaling pathways. Additonally, mercury acts as a genotoxin significantly altering the expression of genes that affect cell survival and apoptosis.

Adult↗

PubMed2002

The fate of the terminally differentiated chondrocyte: evidence for microenvironmental regulation of chondrocyte apoptosis.

Chondrocytes contained within the epiphyseal growth plate promote rapid bone growth. To achieve growth, cells activate a maturation program that results in an increase in chondrocyte number and volume and elaboration of a mineralized matrix; subsequently, the matrix is resorbed and the terminally differentiated cells are deleted from the bone. The major objective of this review is to examine the fate of the epiphyseal chondrocytes in the growing bone. Current studies strongly suggest that the terminally differentiated epiphyseal cells are deleted from the cartilage by apoptosis. Indeed, morphological, biochemical, and end-labeling techniques confirm that death is through the apoptotic pathway. Since the induction of apoptosis is spatially and temporally linked to the removal of the cartilage matrix, current studies have examined the apoptogenic activity of Ca(2+)-, Pi-, and RGD-containing peptides of extracellular matrix proteins. It is observed that all of these molecules are powerful apoptogens. With respect to the molecular mechanism of apoptosis, studies of cell death with Pi as an apoptogen indicate that the anion is transported into the cytosol via a Na(+/)Pi transporter. Subsequently, there is activation of caspases, generation of NO, and a decrease in the thiol reserve. Finally, we examine the notion that chondrocytes transdifferentiate into osteoblasts, and briefly review evidence for, and the rationale of, the transdifferentiation process. It is concluded that specific microenvironments exist in cartilage that can serve to direct chondrocyte apoptosis.

Amino Acid Sequence↗

PubMed2002

Matrix regulation of skeletal cell apoptosis II: role of Arg-Gly-Asp-containing peptides.

This investigation was based on the assumption that arg-gly-asp (RGD)-containing peptides are released from the extracellular matrix of bone and cartilage during the remodeling cycle. We asked the question: Can RGD peptides influence skeletal cell viability? Primary human osteoblasts, mouse MC-3T3-E1 cells, and chick chondrocytes were incubated with purified RGD-containing peptides and cell viability was determined. The RGD peptide did not kill osteoblasts, chondrocytes, or MC-3T3-E1 cells. In contrast, RGDS and GRGDSP peptides killed all three cell types. Osteoblast death was quite rapid, occurring within 6 h of treatment. transferase uridyl mediated nick end labeling (TUNEL) and transmission electron microscopy (TEM) analysis indicated that death was mediated by apoptosis. To learn if mitochondria transduced the death signal, cells were treated with RGDS and organelle function was evaluated using a voltage-sensitive fluorescent probe. It was observed that there was no net loss of fluorescence and, hence, it was concluded that mitochondria were not the primary effectors of the apoptotic response. Experiments were performed with enzyme inhibitors to determine the import of the caspase pathway on RGDS-mediated osteoblast apoptosis. Results of these studies, as well as a study conducted using a fluorescent substrate, pointed to caspase 3 mediating the effector stage of the apoptotic process. Finally, using a purified labeled-RGDS peptide, we showed that the molecule was not restricted by the plasma membrane because it was accumulated in the cytosolic compartment. Results of the investigation support the view that resorption of the extracellular matrix generates peptide products that can induce apoptosis of vicinal cells.

3T3 Cells↗

PubMedDate not supplied

Stem cell regeneration of the nucleus pulposus.

Low back pain due to disc degeneration is one of the largest health problems faced in this nation when judged by lost work time and direct as well as indirect costs. Many experimental methods are being explored to treat or to reverse the effect of disc degeneration. This article reviews the strategy of a tissue engineering approach to disc regeneration. Mesenchymal stem cells (MSC) such as those obtained from marrow stroma when exposed to the appropriate microenvironment (hypoxia, growth factor, three dimensional culture) differentiate into nucleus pulposus-like cells. These then may be candidates for transplantation and nucleus repopulation. While the work is in its infancy, there is significant optimism that next steps will lead to organ culture models of disc degeneration and regeneration, and ultimately to in vivo rescue of degenerating discs with stem cell treatment.

Humans↗

PubMedDate not supplied

Cell-based therapy for disc repair.

BACKGROUND CONTEXT: One of the most promising therapies for symptomatic disc degeneration involves the implantation of therapeutic cells into the degenerative disc. PURPOSE: In this article, the rationale and approaches for cell-based tissue engineering of the intervertebral disc are discussed. STUDY DESIGN: The scientific literature related to cell-based tissue engineering of the intervertebral disc is reviewed. METHODS: A variety of cell types have been used in various research models to affect matrix repair of the intervertebral disc. The use of cellular scaffolds and growth factors or genes also appears promising for achieving meaningful tissue repair of the intervertebral disc. RESULTS: Disc tissue engineering is a promising approach for achieving repair of the intervertebral disc. Using cell-based approaches, various research models suggest that improvements in the complex matrix of the disc may be achieved. CONCLUSION: A cell-based approach to repair of the intervertebral disc appears promising. More research is needed to define the optimal cell type, cellular scaffold and mixture of growth factors that may allow meaningful repair of the human symptomatic degenerative disc.

Animals↗