Systemic administration of IGF-I enhances healing in collagenous extracellular matrices: evaluation of loaded and unloaded ligaments

BACKGROUND: Insulin-like growth factor-I (IGF-I) plays a crucial role in wound healing and tissue repair. We tested the hypotheses that systemic administration of IGF-I, or growth hormone (GH), or both (GH+IGF-I) would improve healing in collagenous connective tissue, such as ligament. These hypotheses were examined in rats that were allowed unrestricted activity after injury and in animals that were subjected to hindlimb disuse. Male rats were assigned to three groups: ambulatory sham-control, ambulatory-healing, and hindlimb unloaded-healing. Ambulatory and hindlimb unloaded animals underwent surgical disruption of their knee medial collateral ligaments (MCLs), while sham surgeries were performed on control animals. Healing animals subcutaneously received systemic doses of either saline, GH, IGF-I, or GH+IGF-I. After 3 weeks, mechanical properties, cell and matrix morphology, and biochemical composition were examined in control and healing ligaments. RESULTS: Tissues from ambulatory animals receiving only saline had significantly greater strength than tissue from saline receiving hindlimb unloaded animals. Addition of IGF-I significantly improved maximum force and ultimate stress in tissues from both ambulatory and hindlimb unloaded animals with significant increases in matrix organization and type-I collagen expression. Addition of GH alone did not have a significant effect on either group, while addition of GH+IGF-I significantly improved force, stress, and modulus values in MCLs from hindlimb unloaded animals. Force, stress, and modulus values in tissues from hindlimb unloaded animals receiving IGF-I or GH+IGF-I exceeded (or were equivalent to) values in tissues from ambulatory animals receiving only saline with greatly improved structural organization and significantly increased type-I collagen expression. Furthermore, levels of IGF-receptor were significantly increased in tissues from hindlimb unloaded animals treated with IGF-I. CONCLUSION: These results support two of our hypotheses that systemic administration of IGF-I or GH+IGF-I improve healing in collagenous tissue. Systemic administration of IGF-I improves healing in collagenous extracellular matrices from loaded and unloaded tissues. Growth hormone alone did not result in any significant improvement contrary to our hypothesis, while GH + IGF-I produced remarkable improvement in hindlimb unloaded animals

The use of mesenchymal stem cells for cartilage repair and regeneration: a systematic review.

BACKGROUND: The management of articular cartilage defects presents many clinical challenges due to its avascular, aneural and alymphatic nature. Bone marrow stimulation techniques, such as microfracture, are the most frequently used method in clinical practice however the resulting mixed fibrocartilage tissue which is inferior to native hyaline cartilage. Other methods have shown promise but are far from perfect. There is an unmet need and growing interest in regenerative medicine and tissue engineering to improve the outcome for patients requiring cartilage repair. Many published reviews on cartilage repair only list human clinical trials, underestimating the wealth of basic sciences and animal studies that are precursors to future research. We therefore set out to perform a systematic review of the literature to assess the translation of stem cell therapy to explore what research had been carried out at each of the stages of translation from bench-top (in vitro), animal (pre-clinical) and human studies (clinical) and assemble an evidence-based cascade for the responsible introduction of stem cell therapy for cartilage defects. This review was conducted in accordance to PRISMA guidelines using CINHAL, MEDLINE, EMBASE, Scopus and Web of Knowledge databases from 1st January 1900 to 30th June 2015. In total, there were 2880 studies identified of which 252 studies were included for analysis (100 articles for in vitro studies, 111 studies for animal studies; and 31 studies for human studies). There was a huge variance in cell source in pre-clinical studies both of terms of animal used, location of harvest (fat, marrow, blood or synovium) and allogeneicity. The use of scaffolds, growth factors, number of cell passages and number of cells used was hugely heterogeneous. SHORT CONCLUSIONS: This review offers a comprehensive assessment of the evidence behind the translation of basic science to the clinical practice of cartilage repair. It has revealed a lack of connectivity between the in vitro, pre-clinical and human data and a patchwork quilt of synergistic evidence. Drivers for progress in this space are largely driven by patient demand, surgeon inquisition and a regulatory framework that is learning at the same pace as new developments take place

The Potential of microRNAs for Stem Cell-based Therapy for Degenerative Skeletal Diseases

Purpose of review: degenerative skeletal disorders including osteoarthritis (OA) and osteoporosis (OP) are the result of attenuation of tissue regeneration and lead to painful conditions with limited treatment options. Preventative measures to limit the onset of OA and OP remain a significant unmet clinical need. MicroRNAs (miRNAs) are known to be involved in the differentiation of stem cells, and in combination with stem cell therapy could induce skeletal regeneration and potentially prevent OA and OP onset.Recent findings: the combination of stem cells and miRNA has been successful at regenerating the bone and cartilage in vivo. MiRNAs, including miR-146b known to be involved in chondrogenic differentiation, could provide innovative targets for stem cell-based therapy, for the repair of articular cartilage defects forestalling the onset of OA or in the generation of a stem cell-based therapy for OP.Summary: this review discusses the combination of skeletal stem cells (SSCs) and candidate miRNAs for application in a cell-based therapy approach for skeletal regenerative medicine

Suturing versus immobilization of a muscle laceration. A morphological and functional study in a mouse model

Muscle laceration remains a difficult problem for orthopaedic surgeons. Despite many studies related to the muscle's ability to regenerate after muscle degeneration, very few reports are available regarding structural and functional recovery after skeletal muscle laceration. We developed an animal model of muscle laceration in mice, where the gastrocnemius muscles were reproducibly transected. We compared the effect of a surgical repair versus a short period of immobilization (5 days) on the muscle healing. The natural course of muscle recovery was monitored at several points after injury using histologic, immunohistochemical, and functional testing. In the injured muscle, we observed a high number of regenerating myofibers and development of fibrotic scar tissue. Suturing the lacerated muscle immediately after injury promoted better healing of the injured muscle and prevented the development of deep scar tissue in the lacerated muscle; conversely, immobilization resulted in slower muscle regeneration and the development of a large area of scar tissue. Tetanus strength 1 month after injury was 81% of control muscles for the sutured muscles, 35% for the lacerated muscles with no treatment, and 18% for the immobilized muscles. Based on this study, suturing a muscle laceration with a modified Kessler stitch results in the best morphologic and functional healing

Direct-, fibroblast- and myoblast-mediated gene transfer to the anterior cruciate ligament

The anterior cruciate ligament (ACL) has poor capabilities of healing. Maturation or "ligamentization" of the ACL following autograft or allograft reconstruction has been found slow and remains under investigation. In vitro and in vivo studies have shown that platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-beta), and epidermal growth factor (EGF) have the potential to improve ligament healing. Gene therapy approaches may represent a new alternative in delivering these specific growth factors to the ACL. The aim of this study was to investigate the feasibility of three different gene therapy approaches (direct-, fibroblast-, and myoblast-mediated gene transfer) to the ACL. Rabbit myoblasts and ACL-fibroblasts were transduced with 5 x 10(7) recombinant adenoviral particles carrying the LacZ reporter gene (MOI = 50). Myoblasts and fibroblasts (1 x 10(6)) were each injected into the right ACL of 10 adult rabbits; direct injection of 5 x 10(7) adenoviral particles was performed in 10 other rabbits. The left side was used as sham. The beta-galactosidase production was revealed using the LacZ histochemical technique. The transduced fibroblasts and myoblasts were found in the ligament tissue and in the synovial tissue surrounding the ACL at 4, 7, 14, and 21 days postinjection. The myoblasts fused and formed myotubes in the ligament. The direct approach also allowed the transfer of the marker gene in the ligament at 4, 7, 21, and 42 days postinjection. X-gal staining revealed no expression of beta-galactosidase in the sham ligament. The presence of cells expressing the marker gene in the ACL opens up the possibility of delivering proteins (i.e., PDGF, TGF-beta, and EGF) capable of improving ACL healing and graft maturation. Furthermore, engineered myoblasts may mediate and accelerate the intraligament neovascularization. This new technology based on gene therapy and tissue engineering may allow a persistent expression of selected growth factors to enhance ACL healing following injury