Biomedical subjects

M Fini

Publications and source records attributed to M Fini.

At least 55 records · Page 3Linked to original sources

PubMed2004

New polymers for drug delivery systems in orthopaedics: in vivo biocompatibility evaluation.

The use of biodegradable polymers for drug delivery systems excluded the need for a second operation to remove the carrier. However, the development of an avascular fibrous capsule, reducing drug release, has raised concern about these polymers in terms of tissue-implant reaction. Five novel polymers were evaluated in vivo after implantation in the rat dorsal subcutis and compared to the reference polycaprolactone (PCL). Poly(cyclohexyl-sebacate) (PCS), poly(L-lactide-b-1,5-dioxepan-2-one-b-L-lactide) (PLLA-PDXO-PLLA), two 3-hydroxybutyrate-co-3-hydroxyvalerate copolymers (D400G and D600G), and a poly(organo)phosphazene (POS-PheOEt:Imidazole) specimens were histologically evaluated in terms of the inflammatory tissue thickness and vascular density at 4 and 12 weeks from surgery. The highest values of inflammatory tissue thickness were observed in D600G (P < 0.01), PCS (P < 0.001) and PLLA-PDXO-PLLA (P < 0.001) at 4 weeks, while POP-PheOEt:Imidazole showed the lowest value of inflammatory tissue thickness (P < 0.05) at 12 weeks. D400G, D600G, PLLA-PDXO-PPLA and POP-PheOEt:Imidazole showed higher (P < 0.001) values of vascular density near the implants in comparison to PCL at 4 weeks. Finally, D400G and D600G increased their vessel densities while POP-PheOEt:Imidazole and the synthetic polyester PLLA-PDXO-PLLA presented similar vessel density values during experimental times. These different behaviours to improve neoangiogenesis without severe inflammatory tissue-responses could be further investigated with drugs in order to obtain time-programmable drug delivery systems for musculoskeletal therapy.

Animals↗

PubMed2004

Adsorption of cationic antibacterial on collagen-coated titanium implant devices.

Two different cationic antimicrobial molecules, chlorhexidine (CH) and poly(hexamethylenebiguanide) (PH), were adsorbed from aqueous solution to titanium implant devices surface-modified by the covalent coupling of collagen on a polyanionic acrylic acid overlayer. Results show that more antimicrobial was adsorbed on surface modified implants as compared to control titanium devices. Moreover, the kinetic of release was affected by the interaction between the polyanionic overlayer and the cationic antimicrobial, leading to slower kinetic of release in the case of CH and stable adsorption in the case of polycationic PH . These data indicate that biochemically modified collagen coated surfaces could be endowed also by antimicrobial properties, in the spirit of present researches on multifunctional implant surfaces.

Adsorption↗

PubMed2004

Osteoporosis and biomaterial osteointegration.

Biomaterial osteointegration depends not only on the properties of the implanted material but also on the characteristics and regenerative capability of the host bone. For this reason, researchers involved in biomaterial evaluation now place great importance on the various pathologies often present in orthopaedic patients which can negatively affect the success of surgical implants. Osteoporosis is undoubtedly one of the most frequently encountered of such diseases. Models reproducing the osteoporotic condition can be useful to understand the influence of the pathology on cell behaviour, bone regeneration and osteointegration processes, thus increasing our basic knowledge and allowing the development of surgical techniques and implant biomaterials more suitable for use in the surgical treatment of fractures in osteoporotic patients. The present paper is a literature review and, after a short description of how the presence of osteoporosis could influence bone regenerative processes, the results of the main studies on biomaterial biocompatibility and osteointegration both in vitro and in vivo in the presence of osteoporotic condition are reported. Both cell cultures and animal models are able to demonstrate the different response of bone to biomaterials by comparing healthy and pathological conditions. The use of pathological bone-derived cells and pathological animals is therefore recommended to test candidate orthopaedic materials.

Animals↗

PubMed2004

Different diagnostic techniques for the assessment of cortical bone on osteoporotic animals.

The aim of this study was to assess the capability of ultrasonography and densitometry to predict the mechanical competence of cortical bone in healthy and osteopenic rats, respectively. Thirty 10-month-old Sprague-Dawley retired breeder female rats were used and randomized into three groups of 10 animals each. A group underwent bilateral ovariectomy by dorsal approach (Ovx), another group underwent a simulated ovariectomy (Sham-Ovx), and the last group served as a sham-aged control group (Control). Sixteen weeks after surgery, the animals were euthanized and the femurs of each rat excised for ultrasonographic and densitometric measurements, and mechanical analyses. The Ovx Group had a significantly decreased amplitude dependent speed of sound (AD-SoS-about 7-8%) when compared to the other groups (p<0.0005). For Ovx animals compared with Sham-Ovx and Control rats, significant decreases in densitometric data were observed (6-13%), as well as significant decreases in femoral Max. Load (about 18%) and flexural rigidity (about 30%). The best correlation (R2=0.55, p<0.0005) found was between SoS and femoral shaft bone mineral density (SBMD). The regression coefficient R2 increased when power-law fits were used, particularly from 0.34 (p<0.001) to 0.36 (p<0.0005) in the correlation between SoS and Max. Load and from 0.21 (p<0.05) to 0.25 (p<0.01) in the correlation between SBMD and Max. Load. The ability of QUS or DXA to accurately predict the actual mechanical characteristics of bone, and in particular bone elasticity, remained relatively poor and the improvement of the power-law model did not describe exhaustively the relationships between the variables tested. The DXA and QUS capability to discriminate between ovariectomized and non-ovariectomized rats did not improve when tested together.

Absorptiometry, Photon↗

PubMed2004

Comparative vascular effects of hormone replacement therapy and raloxifene in women at increased cardiovascular risk.

Hormone replacement therapy (HRT) improves endothelial function in postmenopausal women while the effects of raloxifene, a selective estrogen receptor modulator, are still under debate. The aim of this study was to evaluate endothelium-dependent flow-mediated vasodilatation in the brachial artery and plasma levels of nitrite, nitrate and endothelin-1 in 20 postmenopausal women with increased cardiovascular risk treated with either HRT or raloxifene for 4 weeks in a randomized double-blind single cross-over study. Patients had an endothelium-dependent flow-mediated dilatation of 4% prior to initiation of the study. Treatment with HRT resulted in a 67% increase in dilatation compared with baseline (from a 7.4% increase to a 12.4% increase, p < 0.01). Raloxifene treatment resulted in no change in vasodilatation from baseline. Endothelium-dependent dilatation was significantly improved by HRT compared with raloxifene treatment (12.4+/-0.6% vs. 6.1+/-2.0%; p < 0.01). Compared with baseline values, nitrate plus nitrite levels increased significantly (p < 0.05) with HRT but not with raloxifene. Similarly, endothelin-1 decreased from baseline with both treatments, but only the HRT-induced decrease was statistically significant (p < 0.05). In conclusion, HRT improved endothelial function and reduced plasma levels of endothelin-1 in postmenopausal women at risk of coronary artery disease. These beneficial effects were not shared by raloxifene.

Aged↗

PubMed2004

Fibroin hydrogels for biomedical applications: preparation, characterization and in vitro cell culture studies.

Silk fibroin hydrogels prepared either by treating a 2% (w/v) silk fibroin aqeuous solution at 4 degrees C (thermgel) or by adding 30% (v/v) of glycerol (glygel), were characterized by using Environmental Scanning Electron Microscopy (ESEM), Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), Thermogravimetrical Analysis (TGA) and molecular weight determination. The preparation procedure affected morphology and molecular weight of hydrogels, with no or negligible differences being displayed by FT-IR and DSC analyses. While thermgel presented a well uniform porous structure, the morphology of glygel appeared to be non-porous and heterogeneous. Glygel presented lower water content and lower degradation temperatures, associated with the presence of glycerol but likely also to less-organized protein structures. Cytoxicity tests with human osteoblast-like cells indicated that both gels were not cytoxic, while cell cultures pointed out a faster cell proliferation on glygel and a higher cell activation and differentiation on thermgel. These gels could be used as scaffolds able to promote in situ bone regeneration.

Animals↗

PubMed2004

Biomedical coatings to improve the tissue-biomaterial interface.

One of the most important factors determining the degree of tissue interaction of an implanted device is the property of its surface. Thus, great importance is given to chemical and morphological characteristics of biomaterial surfaces to improve biocompatibility, cell migration, proliferation and differentiation, mechanical stability and endogenous tissue ingrowth. In order to obtain new and healing stimulating properties, it is possible to apply a coating or more generally a surface treatment to the surface of a prosthetic device. One of the most versatile methods for coating is thermal spray technology. This paper considers the principle of thermal spray processes and their application in the biomedical field, namely the coatings used for orthopedic prostheses and dental implants. Among thermal spray processes, plasma spray as well as High Velocity Oxygen Fuel (HVOF) processes will be particularly considered and their most important aspects will be illustrated.

Bone Substitutes↗

PubMed2004

In vitro models to test orthopedic biomaterials in view of their clinical application in osteoporotic bone.

The development of in vitro cell cultures, in association with in vivo experimentation, greatly improved the characterization of biomaterials for orthopedic devices before their clinical use. In recent years an increasing interest has arisen in the use of both pathological osteoblast cultures and animal models to perform in vitro and in vivo tests on biomaterial behavior. A growing number of prostheses, in fact, are implanted in osteoporotic patients, due to the increasing age of the population. Moreover, the presence of osteoporosis may affect bone-biomaterial osteointegration in these patients. The present paper is a literature review and, after a short description of in vitro studies for characterization of osteoblasts derived from osteoporotic bone, the results of in vitro studies on biomaterial biocompatibility and osteointegration rate in the presence of osteoporotic bone derived osteoblast cultures are reported. Pathological cell culture models are able to demonstrate the different behavior of osteoblasts in response to biomaterials, when comparing normal and pathological conditions.

Animals↗

PubMed2004

A biomimetic gelatin-calcium phosphate bone cement.

The interest in new bone substitutes is rapidly increasing in the field of orthopedic surgery. A variety of calcium phosphate bone cement has been developed and different additives have been used to improve their biocompatibility and bioactivity. Following a biomimetic strategy aimed at reproducing bone characteristics, this study investigates the biological properties of a new gelatin enriched calcium phosphate cement (GEL-CP) that exhibits improved mechanical properties with respect to cement prepared without gelatin (C-CP). Human osteoblast MG63 were cultured on the surfaces of GEL-CP and were compared to cells cultured on C-CP samples, and on polystyrene of plate culture as control (C). Cell attachment, proliferation and differentiation were evaluated up to 21 days. SEM revealed that osteoblasts grown on GEL-CP showed a normal morphology and biological tests demonstrated very good rate of proliferation and viability in every experimental time. The presence of gelatin stimulated alkaline phosphatase activity, collagen and transforming growth factor 31 production. The data indicate that the new cement GEL-CP favors osteoblast proliferation, activation of their metabolism and differentiation. The remarkable improvement of the setting properties of the calcium phosphate cement due to the presence of gelatin suggest that the biomimetic composite material could be successfully applied as bone substitute.

Alkaline Phosphatase↗

PubMed2004

Poly(2-hydroxyethyl methacrylate) biomimetic coating to improve osseointegration of a PMMA/HA/glass composite implant: in vivo mechanical and histomorphometric assessments.

Bone implants must simultaneously satisfy many requirements, even though the surface properties remain a crucial aspect in osseointegration success. Since a single material with a uniform structure cannot satisfy all of these requirements, composite materials specifically designed for orthopedic or dental implant application should be envisaged. Two poly(methylmethacrylate)/hydroxyapatite composites reinforced by E-glass fibres, uncoated (PMMA/HA/Glass) and poly(2-hydroxyethyl methacrylate) (PMMA/HA/Glass+pHEMA) coated by the biomimetic method, were mechanically (push-out test) and histomorphometrically (Affinity Index, AI) investigated in an in vivo rabbit model. Cylindrical implants (diameter 2 mm x 5 mm length) were inserted into rabbit femoral cortical (mid-diaphysis) and cancellous (distal epiphysis) bone, under general anesthesia. The highest values of push-out force and ultimate shear strength were observed for the PMMA/HA/Glass at 12 weeks, which significantly (p < 0.001) differed from those of PMMA/HA/Glass+pHEMA at the same experimental time and from those of PMMA/HA/Glass at 4 weeks. At both experimental times, significantly (p < 0.0005) lower values of AI were observed in the PMMA/HA/Glass+pHEMA versus PMMA/HA/Glass (distal femoral epiphysis: 4 weeks = 33%; 12 weeks = 19%; femoral diaphysis: 4 weeks = 15%; 12 weeks = 11%). The good mechanical and histomorphometric results obtained with PMMA/HA/Glass should be followed by further evaluation of bone remodeling processes and mechanical strength around loaded PMMA/HA/Glass implants at longer experimental times. Finally, the biomimetic method applied to pHEMA needs to be further investigated in order to improve the positive effect of SBF on pHEMA and to enhance the coating adhesion.

Animals↗

PubMed2004

Current trends in the enhancement of biomaterial osteointegration: biophysical stimulation.

To enhance bone implant osteointegration, many strategies for improving biomaterial properties have been developed which include optimization of implant material, implant design, surface morphology and osteogenetic coatings. Other methods that have been attempted to enhance endogenous bone healing around biomaterials are different forms of biophysical stimulations such as pulsed electromagnetic fields (PEMFs) and low intensity pulsed ultrasounds (LIPUS), which were initially developed to accelerate fracture healing. To aid in the use of adjuvant biophysical therapies in the management of bone-implant osteointegration, the present authors reviewed experimental and clinical studies published in the literature over the last 20 years on the combined use of biomaterials and PEMFs or LIPUS, and summarized the methodology, and the possible mechanism of action and effectiveness of the different biophysical stimulations for the enhancement of bone healing processes around bone implanted biomaterials.

Animals↗

PubMed2004

Natural and synthetic polyesters for musculoskeletal tissue repair: experimental in vitro and in vivo evaluations.

Two natural Biopol polyesters, containing 8% (D400G) and 12% (D600G) of hydroxyvalerate component, and a synthetic polyester based on 1,4 cyclohexanediol [Poly(cyclohexyl-sebacate)--PCS] were studied to investigate their in vitro and in vivo behavior for application in musculoskeletal tissue repair. The polyesters were placed in direct contact with L929 fibroblasts and cell proliferation (WST-1), cytotoxic effect (LDH), synthetic activity (total proteins) and cytokine production (IL-1beta, IL-6, TNFalpha) were assessed after an incubation period of 72 hours and 7 days. Then, 12 Sprague-Dawley rats underwent dorsal subcutaneous implants of tested polyesters under general anesthesia. After 1 and 4 weeks from surgery, the animals were pharmacologically euthanized and the implants retrieved with surrounding tissue for histologic and histomorphometric investigations. In vitro results showed that D600G behaved a little worse in comparison to other tested polyesters in terms of cell proliferation and TNFa at 7 days. PCS presented the lowest total protein value at 7 days. In vivo results indicated that PCS implants produced a higher (p < 0.01) extent of inflammatory tissue in comparison to D600G at 1 week and to D400G at 4 weeks, and the lowest vascular densities at both experimental times. D400G seems to be the most suitable material for biomedical application when tested in fibroblast cultures and in the subcutaneous tissue of rats.

Animals↗

PubMed2003

Histomorphometric and microhardness assessments of sheep cortical bone surrounding titanium implants with different surface treatments.

Several factors influence the healing process and the long-term mechanical stability of cementless fixed implants, such as bone remodeling and mineralization processes. Histomorphometric and bone hardness measurements were taken in implants inserted in sheep femoral cortical bone at different times to compare the in vivo osseointegration of titanium screws (diam.; 3.5 x 7 mm length) with the following surface treatments: machined (Ti-MA); acid-etched (Ti-HF); HA vacuum plasma spray (Ti-HA); and Ca-P anodization followed by a hydrothermal treatment (Ti-AM/HA). Ti-MA and Ti-AM/HA implants presented the lowest (Ra = 0.20 +/- 0.01 microm) and highest (Ra = 1.97 +/- 0.64 microm) significant (p < 0.0005) roughness value, respectively. Bone-to-implant contact of Ti-HF was lower than that of the other surface treatments at both experimental times (8 weeks: -20%, ns; 12 weeks: -30%, p < 0.01). Significant differences in MAR (mineral apposition rate) were also found between the different experimental times for Ti-MA (115%, p < 0.01) and Ti-HF (57%, p < 0.01), demonstrating that bone growth had slowed inside the screw threads of Ti-HA and Ti-AM/HA after 12 weeks. No bone microhardness changes in preexisting host bone were found, while Ti-MA showed the lowest value for the inner thread area at 8 weeks (HV(200 microm)= 49.8 +/- 3.8 HV). These findings confirm that osseointegration may be accelerated by adequate surface roughness and bioactive ceramic coating such as Ca-P anodization followed by a hydrothermal treatment, which enhance bone interlocking and mineralization.

Animals↗

PubMed2003

Biologic effects of surface roughness and fluorhydroxyapatite coating on osteointegration in external fixation systems: an in vivo experimental study.

The concomitant influence of surface roughness and fluorhydroxyapatite (FHA) coating of titanium (Ti) implants on bone response was investigated. For this purpose, titanium screw-shaped implants with a lower degree (Y371) and a higher degree (TiPore300) of surface roughness, coated with FHA and uncoated, were transversally inserted into the diaphyses of sheep tibiae for 12 weeks. Four sheep received Y371 (group A) and Y371 + FHA (group B) screws and four sheep received TiPore300 (group C) and TiPore300 + FHA (group D) screws. For each type of material, the morphology and microstructure of implant-facing bone were evaluated. The host bone of each tibia was used as a control. In all groups the bone tissue did not reach a complete maturation. The higher degree of roughness, perhaps due to an excessive irregularity of the surface, induced the worst osteointegration: a fibrous tissue layer between screw and new bone tissue was often present. Nevertheless, as viewed by XRD, no crystallographic change of the apatite lattice was observed in any of the implants. In contrast, the microhardness value, an index of bone mineralization, was higher in the uncoated screws and decreased progressively in the following order: group C > group A > group B > group D. The association of plasma spraying with roughness treatment constitutes a complex system that seems to interfere with bone mineralization. A chemical change of the surface, perhaps with more Ti release or more coating degradation, could be responsible for such impairment. The authors emphasize the necessity for simultaneous evaluation of surface topography and chemistry as well as an improvement in plasma-spraying and post-processing techniques and in standard procedures for materials characterization.

Animals↗

PubMed2003

Biological assessment of the bone-screw interface after insertion of uncoated and hydroxyapatite-coated pedicular screws in the osteopenic sheep.

The sheep seems to be a promising model of osteoporosis and biomaterial osteointegration in osteopenic bone. The long-term ovariectomized sheep model was used for the biological investigation of bone healing around uncoated and hydroxyapatite (HA)-coated pedicle screws in osteopenic bone. Four sheep were ovariectomized and four sheep were sham-operated. Twenty-four months after surgery, the animals were implanted with uncoated and HA-coated stainless steel screws in the lumbar vertebral pedicles. Four months later, bone-to-implant contact, bone ingrowth, and bone hardness were measured around screws. Uncoated stainless steel presented significantly (p < 0.0005) lower bone-to-implant contact in healthy and osteopenic bone compared with HA-coated stainless steel. HA significantly improved bone ingrowth in healthy bone (p < 0.05) compared with uncoated stainless steel. Osteopenia significantly (p < 0.05) reduced the area of bone ingrowth around the screw threads for both types of implants. In the inner thread area, bone microhardness significantly increased (p < 0.05) in HA-coated surface versus uncoated for healthy and osteopenic bone. HA coating significantly enhances bone-to-implant contact also in osteopenic bone in comparison with uncoated stainless steel surfaces. Bone ingrowth and mineralization are ameliorated by the osteoconductive HA coating. However, osteopenia seems to greatly influence bone ingrowth processes around the implanted screws regardless of the characteristics of the material surface.

Animals↗

PubMed2003

X-ray micro-diffraction analysis of reconstructed bone at Zr prosthetic surface with sub-micrometre spatial resolution.

The purpose of the present investigation is to demonstrate the power of the x-ray micro-diffraction technique in biological studies. In particular the reported experiment concerns the study of the interface between a Zr prosthetic device implanted in a rat femur and the newly-formed bone, with a spatial resolution of 0.5 microm. The obtained results give interesting information on the Zr deformation and on the crystallographic phase, the grain size and the orientation of the new bone. Moreover the study reveals a marked difference in the structure of the reconstructed bone with respect to the native bone, which cannot be appreciated with other techniques.

Animals↗

PubMed2003

Biomimetic PMMA-based bone substitutes: a comparative in vitro evaluation of the effects of pulsed electromagnetic field exposure.

Pulsed electromagnetic fields (PEMFs) are known to be effective in the stimulation of cultured osteoblasts and in vivo healing of delayed and nonunion fractures. In the present in vitro study the effects of PEMFs on osteoblastic cell cultures (MG63 human osteoblast-like cells) grown in the presence of poly-methylmethacrylate (PMMA) and of a biomimetic bone substitute made of a PMMA matrix added with alfa-tricalcium phosphate (PMMA+alpha-TCP) were evaluated, to assess the biological response at the cell-biomaterial interaction. Cultures were stimulated with PEMFs (75 Hz, 2.3 mT, 1.3-ms pulse duration) 12 h/day for 3 days and evaluations (MTT, ALP, OC, PICP, TGFbeta-1, IL-6) were performed at 3 and 6 days. PMMA had a negative effect on osteoblasts, whereas PMMA+alpha-TCP enhanced production of ALP, PICP, OC and TGFbeta-1, and reduced IL-6 levels. Cells responded positively to PEMF stimulation even when cultured with a poorly biocompatible material, such as PMMA. This effect was more evident in the presence of PMMA+alpha-TCP (further improvement in proliferation and synthetic activity) both at 3 and at 6 days. The properties of PMMA+alpha-TCP look promising, and the present results support the use of PEMFs to improve tissue response to biomaterials implanted as bone substitutes.

Bone Substitutes↗

PubMed2003

"Tumour marker guided" salvage treatment prolongs survival of breast cancer patients: final report of a 7-year study.

OBJECTIVES: Randomised trials on breast cancer showed no significant benefit from post-operative follow-up with clinical and/or conventional radiological means. We hypothesised that carcinoembryonic antigen (CEA), tissue polipeptyde antigen (TPA), breast cancer associated antigen 115 D8/DF3 (CA15.3) tumour marker panel is sensitive enough for significantly anticipating salvage treatment and prolonging survival of relapsing breast cancer patients. METHODS: From October 1981 to May 1999, 68 (62%) of 109 patients with distant metastases were recruited. Thirty-six (53%) received salvage treatment at the time of significant increase in one or more components of CEA-TPA-CA15.3 tumour marker panel and negative instrumental examinations ("tumour marker guided" treatment) and 32 (47%) were treated only after radiological confirmation of metastases (conventional treatment). The prognostic factors of the two groups did not show any statistically significant difference. RESULTS: The time from one or more tumour marker increase to clear clinical and/or radiological signs of distant metastases (lead time) was significantly prolonged in the 36 patients with "tumour marker guided" treatment (17.3 +/- 13.1 vs. 2.9 +/- 2.9 months, P < 0.001, Wilcoxon test) as well as the survival curves from salvage therapy and from mastectomy (the proportion of survivors was: at 36 months from salvage therapy 28% vs. 9%, P = 0.0094; at 84 months from mastectomy 42% vs. 19%, P = 0.0017). The multivariate Cox analysis showed that time from mastectomy to tumour marker increase and "tumour marker guided" salvage treatment were the only significantly different variables (P = 0.00001 and 0.005, respectively). CONCLUSION: These data point out that "tumour marker guided" salvage treatment significantly prolongs disease-free and overall survivals of relapsing responsive patients.

Biomarkers, Tumor↗