The objective of the study was to test the hypothesis that platelet-rich plasma (PRP) enhances meniscal tissue regeneration in vitro and in vivo. In the in vitro study, monolayer meniscal cell cultures were prepared, and 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt assay and 5-bromo-2'-deoxyuridine assay were performed to assess proliferative behavior in the presence of PRP. Alcian blue assay was performed to assess extracellular matrix (ECM) synthesis. To detect the fibrocartilage-related messenger ribonucleic acid (mRNA) expressions, real-time polymerase chain reaction was performed. In the in vivo study, 1.5-mm-diameter full-thickness defects were created in the avascular region of rabbit meniscus. Gelatin hydrogel (GH) was used as the drug delivery system for PRP growth factors. The defects were filled as follows: Group A, GH with PRP; Group B, GH with platelet-poor plasma; Group C, GH only. Each group was evaluated histologically at 4, 8, and 12 weeks after surgery. PRP stimulated deoxyribonucleic acid synthesis and ECM synthesis (p<0.05). Meniscal cells cultured with PRP showed greater mRNA expression of biglycan and decorin (p<0.05). Histological findings showed that remnants of gelatin hydrogels existed at 4 weeks, indicating that the hydrogels could control release for approximately 4 weeks. Histological scoring of the defect sites at 12 weeks revealed significantly better meniscal repair in animals that received PRP with GH than in the other two groups. These findings suggest that PRP enhances the healing of meniscal defects.

Necrotic bone exposure in the oral cavity has recently been reported in patients treated with nitrogen-containing bisphosphonates as part of their therapeutic regimen for multiple myeloma or metastatic cancers to bone. It has been postulated that systemic conditions associated with cancer patients combined with tooth extraction may increase the risk of osteonecrosis of the jaw (ONJ). The objective of this study was to establish an animal model of bisphosphonate-related ONJ by testing the combination of these risk factors. The generation of ONJ lesions in rats resembling human disease was achieved under the confluence of intravenous injection of zoledronate (ZOL; 35 µg/kg every 2 weeks), maxillary molar extraction, and vitamin D deficiency [VitD(−)]. The prevalence of ONJ in the VitD(−)/ZOL group was 66.7%, which was significantly higher (p < .05, Fisher exact test) than the control (0%), VitD(−) (0%), and ZOL alone (14.3%) groups. Similar to human patients, rat ONJ lesions prolonged the oral exposure of necrotic bone sequestra and were uniquely associated with pseudoepitheliomatous hyperplasia. The number of terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate–biotin nick-end label–positive (TUNEL+) osteoclasts significantly increased on the surface of post–tooth extraction alveolar bone of the VitD(−)/ZOL group, where sustained inflammation was depicted by [18F]fluorodeoxyglucose micro-positron emission tomography (µPET). ONJ lesions were found to be associated with dense accumulation of mixed inflammatory/immune cells. These cells, composed of neutrophils and lymphocytes, appeared to juxtapose apoptotic osteoclasts. It is suggested that the pathophysiologic mechanism(s) underpinning ONJ may involve the interaction between bisphosphonates and compromised vitamin D functions in the realm of skeletal homeostasis and innate immunity. © 2010 American Society for Bone and Mineral Research.

The bile salts secretion was studied in ten normal subjects and sixteen patients with alcoholic cirrhosis, in a basal period and during 60 minutes after Secretin injection. Total bile salts were measured by a modification of the enzymatic method of Iwata and Yamasaki and the individual bile salts were separated by silica gel thin-layer chromatography. During the 60 minutes after Secretin the mean concentration was 2.88 +/- 2.58 muM/ml in normals and 1.96 +/- 1.25 muM/ml in cirrhotics. The difference is not significant. During the first 20 minutes however the concentration was higher than 3 muM/ml in 8 out of 10 normals and lower than 2 muM/ml in 10 out 16 cirrhotics. The ratios of tri-to dihydroxy bile salts was similar in both groups. The ratios between bile salts conjugated with glycine and with taurine was higher in normals, and the ratio between free to conjugated bile salts was higher in cirrhotics. The lower concentration of total bile salts immediatly after Secretin, the higher proportion of taurin conjugates and of free bile salts could be important factors in the difficulties of fact digestion and absorption frequently found in patients with alcoholic cirrhosis.

Peripheral nerve injuries can result in lifelong disability. Primary coaptation is the treatment of choice when the gap between transected nerve ends is short. Long nerve gaps seen in more complex injuries often require autologous nerve grafts or nerve conduits implemented into the repair. Nerve grafts, however, cause morbidity and functional loss at donor sites, which are limited in number. Nerve conduits, in turn, lack an internal scaffold to support and guide axonal regeneration, resulting in decreased efficacy over longer nerve gap lengths. By comparison, peptide amphiphiles (PAs) are molecules that can self-assemble into nanofibers, which can be aligned to mimic the native architecture of peripheral nerve. As such, they represent a potential substrate for use in a bioengineered nerve graft substitute. To examine this, we cultured Schwann cells with bioactive PAs (RGDS-PA, IKVAV-PA) to determine their ability to attach to and proliferate within the biomaterial. Next, we devised a PA construct for use in a peripheral nerve critical sized defect model. Rat sciatic nerve defects were created and reconstructed with autologous nerve, PLGA conduits filled with various forms of aligned PAs, or left unrepaired. Motor and sensory recovery were determined and compared among groups. Our results demonstrate that Schwann cells are able to adhere to and proliferate in aligned PA gels, with greater efficacy in bioactive PAs compared to the backbone-PA alone. In vivo testing revealed recovery of motor and sensory function in animals treated with conduit/PA constructs comparable to animals treated with autologous nerve grafts. Functional recovery in conduit/PA and autologous graft groups was significantly faster than in animals treated with empty PLGA conduits. Histological examinations also demonstrated increased axonal and Schwann cell regeneration within the reconstructed nerve gap in animals treated with conduit/PA constructs. These results indicate that PA nanofibers may represent a promising biomaterial for use in bioengineered peripheral nerve repair.

The objective of this study was to increase the therapeutic efficacy of anterior cruciate ligament (ACL) surgery using an artificial ligament material developed through a combination of tissue engineering technologies. A poly-L-lactic acid (PLLA) scaffold of plain-woven braid was incorporated with a gelatin hydrogel for controlled release of basic fibroblast growth factor (bFGF) and wrapped with a collagen membrane to allow space for ligament regeneration. For the ACL reconstruction surgery, the PLLA braid scaffold combined with the gelatin hydrogel incorporating bFGF and the collagen wrapping was applied to a tunnel prepared in the femur and tibia of rabbits. The hydrogel was placed in the bone, whereas the portion of the braid inside the joint cavity was wrapped with the membrane. As controls, the PLLA scaffold was applied with the hydrogel or the membrane, or without either material. Bone regeneration in the tunnel and ACL tissue regeneration in the joint cavity were histologically evaluated, and the mechanical strength and collagen content of the regenerated ACL were assessed. When the PLLA scaffold was integrated with both the hydrogel and the membrane, bone and ACL tissues were regenerated in the corresponding sites, in marked contrast to the control groups. Combination of bFGF-controlled release resulted in enhanced mechanical strength of the regenerated ACL tissue. In the joint cavity, it is possible that the local bFGF release inside the membrane enhanced the cell migration and collagen production, and that the surrounding PLLA scaffold results in the biological regeneration of ligament-like tissue. Additionally, significant bone regeneration around the scaffold was observed in the bone tunnel. It is therefore possible that the local controlled release of bFGF near the PLLA braid induced both osseointegration and intrascaffold cell migration in the bone tunnel and joint cavity, respectively, resulting in an overall increase in the mechanical strength of the regenerated ACL.

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Bisphosphonates (BPs) are chemically stable analogs of pyrophosphate exhibiting strong affinity to bone and have been used for the treatment of diseases characterized by excessive bone resorption. Contrary to the widely accepted BP accumulation model in bone after repeated applications, we report here that an equilibrium-dependent BP-crystalline bone mineral interaction may better explain BP bio-distribution and anti-catabolic bone remodeling and may be relevant to the appearance of osteonecrosis of the jaw (ONJ) in rats. Fluorescent-labeled BP analogs were synthesized and used to evaluate the mode of bone adsorption. After fluorescent-labeled BP adsorbed on crystalline calcium phosphates in vitro, subsequent BP application replaced the previously absorbed BP depending on the dose and the relative binding affinity to hydroxyapatite. The in vivo intravenous zoledronate (ZOL) injection of repeated fractional doses resulted in lower serum CTX and TRAP5b measurements than a single bolus injection in spite of the equivalent cumulative dose. Repeated injections resulted in the distribution of fluorescent-labeled BP on the large area of bone surfaces; whereas the single bolus injection gave rise to the intense BP bio-distribution at selected bone sites such as the alveolar process of jawbones. Necrotic maxillary alveolar bone was predominantly observed in vitamin D deficiency rats treated with bolus ZOL injection. The palatal necrotic bone was characteristically sequestrated by the fistulation of hyperplastic oral epithelium, suggesting the initial development of ONJ-like lesions in rats. Our results suggest that equilibrium-dependent BP-bone interaction may, in part, determine the effectiveness and influence side effects of long-term and repeated applications of BPs.