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PubMed2006

Design and analysis of tissue engineering scaffolds that mimic soft tissue mechanical anisotropy.

Tissue engineered constructs must exhibit tissue-like functional properties, including mechanical behavior comparable to the native tissues they are intended to replace. Moreover, the ability to reversibly undergo large strains can help to promote and guide tissue growth. Electrospun poly (ester urethane) ureas (ES-PEUU) are elastomeric and allow for the control of fiber diameter, porosity, and degradation rate. ES-PEUU scaffolds can be fabricated to have a well-aligned fiber network, which is important for applications involving mechanically anisotropic soft tissues. We have developed ES-PEUU scaffolds under variable speed conditions and modeled the effects of fiber orientation on the macro-mechanical properties of the scaffold. To illustrate the ability to simulate native tissue mechanical behavior, we demonstrated that the high velocity spun scaffolds exhibited highly anisotropic mechanical properties closely resembling the native pulmonary heart valve leaflet. Moreover, use of the present fiber-level structural constitutive model allows for the determination of electrospinning conditions to tailor ES-PEUU scaffolds for specific soft tissue applications. The results of this study will help to provide the basis for rationally designed mechanically anisotropic soft tissue engineered implants.

Anisotropy↗
PubMed2006

Quality control in tissue banking--ensuring the safety of allograft tissues.

DESPITE FEDERAL REGULATIONS for tissue-banking practices, inadequate quality control led to the largest allograft tissue recall in history in October 2005. THE RECALL INCLUDED all allograft tissues obtained from 761 donors and distributed by five tissue banks. Many of these tissues already had been implanted and were unrecoverable. THIS ARTICLE DESCRIBES the many tissue-banking industry variables, including donor selection and testing and tissue recovery, processing, and preservation. QUESTIONS THAT HEALTH CARE providers can ask to determine which tissue banks' quality control measures best ensure the safety of the allografts they provide also are included.

Communicable Disease Control↗
PubMed2001

Expression of matrix metalloproteinase (MMP-1) and tissue inhibitor of MMP in serosal tissue of intraperitoneal organs and adhesions.

OBJECTIVE: To compare expression of matrix metalloproteinase (MMP-1) and tissue inhibitor of MMP (TIMP-1) in serosal tissue of intraperitoneal organs and adhesions. DESIGN: Prospective and cross-sectional study. SETTING: Academic research centers. PATIENT(S): Patients undergoing abdominal or pelvic surgery. INTERVENTION(S): MMP-1 and TIMP-1 expression. MAIN OUTCOME MEASURE(S): Expression of messenger ribonucleic acid (mRNA) and protein was measured by using quantitative reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay. RESULT(S): Serosal tissue of intraperitoneal organs and adhesions express MMP-1 and TIMP-1 mRNA and protein at levels that are consistently varied with 10- to 10,000-fold and 2- to 10-fold higher TIMP, mRNA and protein, respectively. Parietal peritoneum, fallopian tubes and ovaries express higher MMP-1 mRNA levels compared with uterus and adhesions; the lowest expression is found in small and large bowels, subcutaneous tissue. and omentum. Expression of TIMP-1 mRNA was less variable; the highest level was found in the uterus and the lowest in subcutaneous tissue and small bowels. There was less variability in MMP-1 and TIMP-1 protein content than mRNA expression; ovaries and adhesions contained the highest MMP-1 and TIMP-1 levels, respectively, and peritoneum contained the lowest. The MMP-1 and TIMP-1 content and ratios further indicate limited MMP-1 proteolytic activity. Although tissues from premenopausal women express more MMP-1 and TIMP-1, expression did not differ by sex or age. CONCLUSION(S): Because MMP-1 and TIMP-1 expression varies consistently among the serosal tissues of peritoneal organs and adhesions, and because tissue injury alters their expression, site-specific variations in expression of these substances may predispose a particular organ to develop more adhesions.

Abdomen↗
PubMed1994

Implant-tissue interfaces following treatment of peri-implantitis using guided tissue regeneration: a light and electron microscopic study.

This study details the structural and ultrastructural features of the interfaces between titanium implants and their surrounding tissues. The material stemmed from an experiment in dogs in which guided tissue regeneration with Gore-Tex membranes was used to treat peri-implant, ligature-induced tissue breakdown around submerged and nonsubmerged commercially pure titanium implants. Specimens from the nonsubmerged group were evaluated under light microscopy and scanning and transmission electron microscopy. A healthy gingiva and a gingival sulcus were formed around the implant necks. A regenerated junctional epithelium provided the epithelial union between implant and gingiva. The supracrestal connective tissue was characterized by a 3-dimensional network of collagen fibers, fibroblasts and blood vessels. Near the implant surface the collagen fibers ran parallel to the titanium surface or were orientated perpendicular to the implant. The connective tissue-implant interface was characterized by a fine fibrillar material interposed between the implant surface and the connective tissue. An unidentified material was also observed between the endings of functionally orientated collagen fibrils and the metallic surface. The apical portions of the implants were anchored in compact bone. At the bone-implant interface, either mineralized bone matrix was intimately adapted to the titanium surface without any intervening space or a 0.5-micron wide unmineralized layer was interposed. These findings indicate that a perimucosal seal was formed around the implants consisting of a junctional epithelium-implant union coronally and supported by the connective tissue-implant junction apically. The implants were integrated in connective tissue, but only tightly adapted to bone.

Animals↗
PubMed1998

Immunolocalization of matrix metalloproteinases and tissue inhibitors of metalloproteinases in human subconjunctival tissues.

PURPOSE: To evaluate the roles of fibroblast proteins in the remodeling of the subconjunctival connective tissue, we immunohistochemically assessed the expression of matrix metalloproteinases (MMP)-1 and -2, and the tissue inhibitors of matrix metalloproteinases (TIMP)-1 and -2 in cultured human subconjunctival fibroblasts and in normal and healing human subconjunctival connective tissue. METHODS: Cultured fibroblasts derived from human subconjunctival connective tissue and surgical specimens of normal and healing conjunctiva were immunostained with monoclonal antibodies directed against human MMPs and TIMPs and examined by light and electron microscopy. RESULTS: In the cultured fibroblasts, MMP-1 and TIMP-1 antibodies stained the cytoplasm in a fine granular pattern, suggesting localization of those proteins in the endoplasmic reticulum (ER) and Golgi apparatus. Antibodies to MMP-2 and TIMP-2 reacted with fibroblast cytoplasm in a granular pattern. Electron microscopy of those fibroblasts revealed MMP-1 and TIMP-1 immunoreactivity in the ER cisternae or on the membrane of the ER. In surgical samples, MMP-1 and TIMP-1 were immunohistochemically detected in healing subconjunctival tissue, but not in conjunctival epithelium or normal subconjunctival tissue. CONCLUSIONS: MMPs and TIMPs may be involved in remodeling of subconjunctival connective tissue and in fibroblast population after surgical interventions. These proteins may play a crucial role in the post-operative fibrotic process occurring during scar formation in subconjunctival tissue.

Adult↗
PubMed2004

Tissue regeneration based on tissue engineering technology.

Recent development of biomedical engineering as well as basic biology and medicine has enabled us to induce cell-based regeneration of body tissue to self-repair defective tissue or substitute biological functions of damaged organs. For successful tissue regeneration, it is indispensable to give cells an environment suitable for regeneration induction. Tissue engineering is a newly emerging biomedical technology for creating an environment for tissue regeneration with various biomaterials. The paper presented here overviews recent research data on tissue regeneration based on tissue engineering, and briefly explains the key technology of tissue engineering.

Adipose Tissue↗
PubMed2005

Human research tissue banks: the ATRA Project for establishing a human research tissue bank in switzerland.

A large number of experiments in biomedical research are carried out on tissues, but, even though the results should be applicable to humans, these tissues are mainly of animal origin. The difficulty encountered in obtaining human organs and tissues is an acknowledged problem: not enough human tissues are available to meet research needs. We are introducing the ATRA Project, with the purpose of supporting progress in biomedical research in Switzerland through the establishment of one or more human tissue banks, which will be able to find, treat, preserve and supply human material. Where similar projects have already been launched, concerns have been expressed that donation for research purposes might compete with donation for transplantation, but most organs and tissues are in any case non-transplantable. Surplus surgical tissue is considered "sanitary waste", and must be treated according to specific regulations for collection, packaging, transport, treatment and disposal. A human tissue bank would not only abate the costs of treating sanitary waste, but would actually turn what is now considered waste into a resource which could be used to save human and animal lives.

Animal Testing Alternatives↗
PubMed1991

Measurement of insulin-like growth factor-II in physiological fluids and tissues. II. Extraction quantification in rat tissues.

The tissue distribution and developmental patterns of insulin-like growth factor-II (IGF-II) have not been investigated in rat tissues, primarily because of the lack of an efficient extraction method for IGF-II and a sensitive RIA. IGF-II was extracted from rat tissues by formic acid, and the extract was heated at an acidic pH and treated with acetone. The removal of binding proteins was demonstrated by fast protein liquid chromatography size exclusion column and the elimination of a dilutional bias in the RIA. Using rat IGF-II as standard, we optimized a RIA for the quantification of IGF-II in rat tissues. In adult rats, IGF-II was found in all 15 tissues examined, with the highest concentration in the pituitary, followed by kidney, seminal vesicles, intestine, and serum. This distribution is not only different from that of IGF-I, but also differs from that reported for IGF-II mRNA and IGF-II receptors, suggesting that the rates of synthesis and/or metabolism of IGF-II are tissue dependent. Developmentally, IGF-II levels fell postnatally in most tissues, a pattern similar to that of IGF-II mRNA and IGF-II receptor. This developmental pattern supports the hypothesis that IGF-II is important in early growth and development. A relatively homogeneous distribution was observed in the adult rat brain, a distribution also different from that reported for IGF-II mRNA. In the pituitary, the highest concentration was found in the posterior pituitary, followed by the intermediate and anterior pituitary. In conclusion, IGF-II is found in many tissues of adult rats. This observation supports an autocrine and/or paracrine roles for IGF-II.

Animals↗
PubMed2000

Dietary n-3 fatty acids affect mRNA level of brown adipose tissue uncoupling protein 1, and white adipose tissue leptin and glucose transporter 4 in the rat.

We examined the effect of dietary fats rich in n-3 polyunsaturated fatty acids (PUFA) on mRNA levels in white and brown adipose tissues in rats. Four groups of rats were fed on a low-fat diet (20 g safflower oil/kg) or a high-fat diet (200 g/kg) containing safflower oil, which is rich in n-6 PUFA (linoleic acid), or perilla (alpha-linolenic acid) or fish oil (eicosapentaenoic and docosahexaenoic acids), both of which are rich in n-3 PUFA, for 21 d. Energy intake was higher in rats fed on a high-safflower-oil diet than in those fed on low-fat or high-fish-oil diet, but no other significant differences were detected among the groups. Perirenal white adipose tissue weight was higher and epididymal white adipose tissue weight tended to be higher in rats fed on a high-safflower-oil diet than in those fed on a low-fat diet. However, high-fat diets rich in n-3 PUFA, compared to a low-fat diet, did not increase the white adipose tissue mass. High-fat diets relative to a low-fat diet increased brown adipose tissue uncoupling protein 1 mRNA level. The increases were greater with fats rich in n-3 PUFA than with n-6 PUFA. A high-safflower-oil diet, compared to a low-fat diet, doubled the leptin mRNA level in white adipose tissue. However, high-fat diets rich in n-3 PUFA failed to increase it. Compared to a low-fat diet, high-fat diets down-regulated the glucose transporter 4 mRNA level in white adipose tissue. However, the decreases were attenuated with high-fat diets rich in n-3 PUFA. It is suggested that the alterations in gene expression in adipose tissue contribute to the physiological activities of n-3 PUFA in preventing body fat accumulation and in regulating glucose metabolism in rats.

Adipose Tissue↗
PubMed2002

Soft tissue sarcoma of the upper extremity: a 5-year experience at two institutions emphasizing the role of soft tissue flap reconstruction.

BACKGROUND: The objective of this study was to define the impact of soft tissue flap reconstruction on multimodality therapy for patients with soft tissue sarcomas of the upper extremity. Treatment standards continue to evolve for these patients, and, with multimodality therapy, most of them are candidates for limb-preserving surgery. Consequently, the role of soft tissue flap reconstruction is expanding. METHODS: A review was conducted of 100 consecutive patients with soft tissue sarcomas of the upper extremity who underwent surgery at several institutions between 1992 and 1997. RESULTS: Seventy-one patients underwent direct closure of defects after tumor resection, and 29 patients required soft tissue reconstruction with flaps. These groups were similar in most respects, except that 52% of the patients who required soft tissue reconstruction presented with recurrent disease (P = 0.0004), and 79% of them had tumors measuring > 5 cm in greatest dimension (P = 0.0003). The patients who required flap reconstruction had larger skin deficits after undergoing tumor resection (140 cm2) compared with the patients who had wounds that were managed by direct closure (40 cm2; P < 0.00001). Margins around the resected tumors were larger (1.62 cm) when flaps were employed compared with margins when defects were closed directly (0.87 cm; P = 0.0005). However, the number of patients with intralesional, marginal, wide, and radical resections was the same regardless of wound management. Major complications occurred in 14% of patients, but none led to death or amputation. The median follow-up was 31 months, and 66% of patients had no evidence of disease at that time. Rates of local recurrence and survival were similar for patients who underwent flap reconstruction compared with patients who underwent direct closure. CONCLUSIONS: Soft tissue flap reconstruction facilitates therapy for patients with soft tissue sarcomas of the upper extremity, so that patients with larger tumors can undergo resection, limiting complications and limb sacrifice.

Adolescent↗
PubMed2001

Enhanced systemic tissue distribution after dermal versus intravenous 3,3',4,4'-tetrachlorobiphenyl exposure: limited utility of radiolabel blood area under the curve and excretion data in dermal absorption calculations and tissue exposure assessment.

As a dioxin-like polychlorinated biphenyl (PCB), 3,3',4,4'-tetrachlorobiphenyl (TCB) is receiving increasing research and regulatory interest due to its high toxicity and persistence in the environment. (14)C-TCB was administered at an identical dose of 300 microg via the intravenous (iv) or dermal route to swine to examine the exposure route dependency of the relationship between tissue exposure and blood area under the curve (AUC) and the relationship between dermal absorption and excretion of radiolabel. After iv and dermal exposure, blood, urine, and feces samples were collected during the 11-day in vivo studies. At the end of the experiments, full mass balance studies were conducted to characterize tissue distribution of label. On average, over 70% of the applied dermal and iv doses were recovered. As expected, more than a 10-fold increase in blood AUC (0.49 vs 0.031, h x % dose/ml), plasma AUC (0.40 vs 0.038, h x % dose/ml), urine excretion (29 vs 2.3% of the applied dose), and fecal (30 vs 3.0% of the applied dose) excretion was determined after iv exposure compared to dermal exposure. However, we unexpectedly found that the tissue residue following iv exposure (8.0% of the applied dose) was only half that following dermal exposure (16% of the applied dose). Significantly larger (20- to 30-fold) ratios of blood AUC:tissue residue and excretion:tissue residue were observed after iv exposure compared to dermal exposure. This may indicate a route-related concentration-dependent blood-to-tissue partition process of pooled label, unique skin metabolism, or saturable hepatic metabolism of TCB. Thus, a long-term, low-input exposure pattern similar to this dermal exposure could be more harmful to systemic tissues than a short-term, high-dose exposure similar to this iv exposure. One should be aware that greater absorption, higher blood concentrations, greater blood and plasma AUCs, and greater excretion of label do not necessarily result in a greater overall tissue exposure and that some conventional approaches using label determination in blood and excreta without full mass balance studies may underestimate dermal absorption of chemicals similar to TCB.

Administration, Cutaneous↗
PubMed2006

Cellular to tissue informatics: approaches to optimizing cellular function of engineered tissue.

Tissue engineering is a rapidly expanding, multi-disciplinary field in biomedicine. It provides the ability to manipulate living cells and biomaterials for the purpose of restoring, maintaining, and enhancing tissue and organ function. Scientists have engineered various tissues in the body, from skin substitutes to artificial nerves to heart tissues, with varying degrees of success. Although the field of tissue engineering has come a long way since its first successful demonstration by Bisceglie in the 1930s, methods of coaxing them into functional tissues have been predominantly empirical to date. To successfully develop tissue-engineered organs, it is important to understand how to maintain the cells under conditions that maximize their ability to perform their physiological roles, regardless of their environment. In that context, a methodology that combines empirical data with mathematical and statistical techniques, such as metabolic engineering and cellular informatics, to systematically determine the optimal (1) type of cell to use, (2) scaffold properties and the corresponding processing conditions to achieve those properties, and (3) the required types and levels of environmental factors and the operating conditions needed in the bioreactor, will enable the design of viable and functional tissues tailored to the specific requirements of individual situations.

Animals↗
PubMed1987

Immunohistochemical procedures for the demonstration of peptide- and tyrosine hydroxylase-containing nerve fibers in cryostat sections of unfixed rapidly frozen tissue stored for long periods of time. A study on heart tissue.

Traditional protocols for the immunohistochemical localization of peptides and tyrosine hydroxylase (TH) in nerve fibers in cryostat sections require the tissue to be thoroughly fixed and rinsed and to be processed for the cryostat sectioning and the immunohistochemical staining more or less directly after freezing. In the present study it was tested whether also unfixed, rapidly frozen tissue, conforming to guinea pig and bovine heart specimens, can be used for the visualization of neuropeptides [neuropeptide Y (NPY) and substance P (S P)] and TH in cryostat sections. The following observations were made: 1) NPY-immunoreactive (IR) and S P-IR nerve fibers could be clearly identified in both fixed and unfixed sections of this type of tissue. 2) TH-IR nerve fibers could be detected in unfixed tissue if the sections were post-fixed with aldehydes by the use of a two-step fixation process related to a sudden change of pH. However, the outlines of the nerve fibers were sometimes diffuse. 3) Storage of unfixed tissue for periods of up to 2.5 years at-80 degrees C did not lead to a decrease in immunoreactivity. 4) Somewhat higher concentrations of primary antibodies had to be used for sections of unfixed tissue than for sections of fixed tissue when the FITC method was used. This waste of antibodies was partly overcome by use of the biotin-streptavidin method. The glyoxylic acid induced catecholamine(CA)-fluorescence method for demonstration of sympathetic nerve fibers was also applied and was found to give optimal results after storage of tissue for up to 2.5 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Tissue localization of methotrexate-monoclonal-IgM immunoconjugates: anti-SSEA-1 and MOPC 104E in mouse teratocarcinomas and normal tissues.

Methotrexate (MTX) was coupled to the tumor-targeting monoclonal IgM, anti-SSEA-1 and the non-targeting myeloma IgM, MOPC 104E. At 24-h intervals following injection, drug deposition in MH-15 teratocarcinomas and in several normal tissues was followed by immunoperoxidase microscopy using the M16 monoclonal antibody to MTX. MTX-anti-SSEA-1 was deposited on the surface and in the interior of living tumor cells 24 h after injection; at 48 h and after, only low-level binding to necrotic tissue was found. There was no significant gradation in staining from the outside to the interior of the tumors. In tumors, the control MOPC 104E immunoconjugate was detectable only in necrotic tissue. Binding to SSEA-1-expressing normal tissues was undetectable, except for pericryptal fibroblasts in the small intestine. No significant pathology was found in normal tissues that are SSEA-1 positive. High levels of the immunoconjugate were detected in the liver, where MTX was found predominantly in Kupffer cells and possibly in hepatocytes; again, no significant morphological changes were associated with this retention. Thus tumor-associated antigens can be suitable targets for antibody-drug conjugates even when present in normal tissues and in large quantities, provided that the antigens in normal tissues are inaccessible. Moreover, deposition in viable tumor tissue can be assessed using monoclonal antibodies to methotrexate.

Animals↗
PubMed2005

Vascular patches tissue-engineered with autologous bone marrow-derived cells and decellularized tissue matrices.

Synthetic polymer vascular patches used in cardiovascular surgery have shortcomings such as thrombosis, intimal hyperplasia, calcification, infection, and no growth potential. Tissue-engineered vascular patches using autologous vascular cells may solve these problems. In this study, we developed a tissue-engineered vascular patch using autologous bone marrow-derived cells (BMCs) and decellularized tissue matrices. Vascular smooth muscle cells and endothelial cells were differentiated from bone marrow mononuclear cells in vitro. Tissue-engineered vascular patches were fabricated by seeding these cells onto decellularized canine inferior vena cava matrices and implanted into the inferior vena cava of dogs. Three weeks after implantation, the tissue-engineered vascular patches were patent with no sign of thrombus formation. Histological, immunohistochemical, and electron microscopic analyses of the vascular patches retrieved 3 weeks after implantation revealed regeneration of endothelium and smooth muscle and the presence of collagen and elastin. BMCs labeled with a fluorescent dye prior to implantation were detected in the retrieved vascular patches, indicating that the BMCs survived after implantation and contributed to the vascular tissue regeneration. This study demonstrates that vascular patches can be tissue-engineered with autologous BMCs and decellularized tissue matrices.

Animals↗
PubMed2006

The effect of anisotropic architecture on cell and tissue infiltration into tissue engineering scaffolds.

A common phenomenon in tissue engineering is rapid tissue formation on the outer edge of the scaffold which restricts cell penetration and nutrient exchange to the scaffold centre, resulting in a necrotic core. To address this problem, we generated scaffolds with both random and anisotropic open porous architectures to enhance cell and subsequent tissue infiltration throughout the scaffold for applications in bone and cartilage engineering. Hydroxyapatite (HA) and poly(D,L-lactic acid) (P(DL)LA) scaffolds with random open porosity were manufactured, using modified slip-casting and by supercritical fluid processing respectively, and subsequently characterised. An array of porous aligned channels (400 microm) was incorporated into both scaffold types and cell (human osteoblast sarcoma, for HA scaffolds; ovine meniscal fibrochondrocytes, for P(DL)LA scaffolds) and tissue infiltration into these modified scaffolds was assessed in vitro (cell penetration) and in vivo (tissue infiltration; HA scaffolds only). Scaffolds were shown to have an extensive random, open porous structure with an average porosity of 85%. Enhanced cell and tissue penetration was observed both in vitro and in vivo demonstrating that scaffold design alone can influence cell and tissue infiltration into the centre of tissue engineering scaffolds.

Animals↗
PubMed2006

Histopathological outcome of 597 isolated soft tissue tumors suspected of soft tissue sarcoma: a single-center 12-year experience.

BACKGROUND: The aim of this present report was to analyze the patients referred to us with the presumptive diagnosis of soft tissue sarcoma (STS). METHODS: We reviewed all patients referred to us with suspected soft tissue sarcoma (STS) of the extremities or trunk over a 12-year period. RESULTS: We treated 597 patients with soft tissue tumors. Open biopsy revealed soft tissue sarcoma in 318 cases, benign mesenchymal tumor in 124 cases and isolated metastases (ISTM) from carcinomas in 98 patients; other pathologies were found in 57 patients. The primary carcinomas were lung cancer in 26 patients, breast cancer in 19 patients, renal carcinoma in 16 patients, carcinoma of the esophagus in 12 patients, colonic carcinoma in 5 patients, thyroid gland cancer in 6 patients, and in 14 patients carcinoma of unknown primary was diagnosed. CONCLUSIONS: In our collective with soft tissue tumor, 50% of the patients had the diagnosis of soft tissue sarcoma, 20% presented with a metastasis of carcinoma and 20% had a benign tumor. Referring to our results, in patients with the presumptive diagnosis of soft tissue sarcomas, soft tissue metastasis of a primary carcinoma was unexpectedly common, indicating that greater consideration should be given to this differential diagnosis.

Adolescent↗
PubMed2004

Biomechanical assessment of tissue retrieved after in vivo cartilage defect repair: tensile modulus of repair tissue and integration with host cartilage.

Failure to restore the mechanical properties of tissue at the repair site and its interface with host cartilage is a common problem in tissue engineering procedures to repair cartilage defects. Quantitative in vitro studies have helped elucidate mechanisms underlying processes leading to functional biomechanical changes. However, biomechanical assessment of tissue retrieved from in vivo studies of cartilage defect repair has been limited to compressive tests. Analysis of integration following in vivo repair has relied on qualitative histological methods. The objectives of this study were to develop a quantitative biomechanical method to assess (1) the tensile modulus of repair tissue and (2) its integration in vivo, as well as determine whether supplementation of transplanted chondrocytes with IGF-I affected these mechanical properties. Osteochondral blocks were obtained from a previous 8 month study on the effects of IGF-I on chondrocyte transplantation in the equine model. Tapered test specimens were prepared from osteochondral blocks containing the repair/native tissue interface and adjacently located blocks of intact native tissue. Specimens were then tested in uniaxial tension. The tensile modulus of repair tissue averaged 0.65 MPa, compared to the average of 5.2 MPa measured in intact control samples. Integration strength averaged 1.2 MPa, nearly half the failure strength of intact cartilage samples, 2.7 MPa. IGF-I treatment had no detectable effects on these mechanical properties. This represents the first quantitative biomechanical investigation of the tensile properties of repair tissue and its integration strength in an in vivo joint defect environment.

Animals↗