Regeneration of Osteonecrosis of Canine Scapho-lunate Using Bone Marrow Stromal Cells: Possible Therapeutic Approach for Kienböck Disease

Article Commentary: Stem Cell Research in Cell Transplantation: An Analysis of Geopolitical Influence by Publications

One of the fastest growing fields in researching treatments for neurodegenerative and other disorders is the use of stem cells. These cells are naturally occurring and can be obtained from three different stages of an organism's life: embryonic, fetal, and adult. In the US, political doctrine has restricted use of federal funds for stem cells, enhancing research towards an adult source. In order to determine how this legislation may be represented by the stem cell field, a retrospective analysis of stem cell articles published in the journal Cell Transplantation over a 2-year period was performed. Cell Transplantation is considered a translational journal from preclinical to clinical, so it was of interest to determine the publication outcome of stem cell articles 6 years after the US regulations. The distribution of the source of stem cells was found to be biased towards the adult stage, but relatively similar over the embryonic and fetal stages. The fetal stem cell reports were primarily neural in origin, whereas the adult stem cell ones were predominantly mesenchymal and used mainly in neural studies. The majority of stem cell studies published in Cell Transplantation were found to fall under the umbrella of neuroscience research. American scientists published the most articles using stem cells with a bias towards adult stem cells, supporting the effect of the legislation, whereas Europe was the leading continent with a bias towards embryonic and fetal stem cells, where research is “controlled” but not restricted. Japan was also a major player in the use of stem cells. Allogeneic transplants (where donor and recipient are the same species) were the most common transplants recorded, although the transplantation of human-derived stem cells into rodents was the most common specific transplantation performed. This demonstrates that the use of stem cells is an increasingly important field (with a doubling of papers between 2005 and 2006), which is likely to develop into a major therapeutic area over the next few decades and that funding restrictions can affect the type of research being performed.

Nerve Regeneration Promoted in a Tube with Vascularity Containing Bone Marrow-Derived Cells

Bone marrow-derived cells (BMCs) are multipotent cells that have the potential to differentiate into bone, cartilage, fat, muscle, or neuronal lineages such as neurons and glial cells. A silicone tube model containing reverse-pedicled sural vessels was created in the sciatic nerves of Lewis rats. About 1 × 107 BMCs, removed from the bone marrow of synergetic rat femurs and cultured in vitro, were transplanted into the 15-mm-long chambers of the silicone tubes. Nerve regeneration in vessel-containing tubes that had received BMCs was significantly greater at 12 and 24 weeks after surgery than in tubes that did not receive cells. Transplantation of fibroblasts instead of BMCs into the vessel-containing tube resulted in reduced axonal regeneration, which was inferior to regeneration in the vessel-containing tube that did not receive cells. Polymerase chain reaction (PCR) studies revealed that in vessel-containing tubes containing transplanted BMCs, about 29% of cells in the regenerated nerve originated from BMCs. Cells identified by in situ hybridization and PKH26 prelabeling as being of BMC origin stained positively for S100 and GFAP. Transplanted BMCs differentiated into cells with phenotypes similar to those of Schwann cells under the influence of neurochemical factors and survived by obtaining nutrients from vessels that had been preinserted into the tube. They thus functioned similarly to Schwann cells, promoting nerve regeneration.

An exploratory clinical trial for idiopathic osteonecrosis of femoral head by cultured autologous multipotent mesenchymal stromal cells augmented with vascularized bone grafts

Idiopathic osteonecrosis of femoral head (ION) is a painful disorder that progresses to collapse of the femoral head and destruction of the hip joint. Although its precise pathology remains unknown, the loss of blood supply causing the loss of living bone-forming cells is a hallmark of the pathophysiology of osteonecrosis. Transplantation of multipotent mesenchymal stromal cells (MSCs) is a promising tool for regenerating the musculoskeletal system. The aim of the present study was to assess the safety and efficacy of transplantation of cultured autologous bone marrow-derived MSCs mixed with β-tricalcium phosphate (β-TCP) in combination with vascularized bone grafts for the treatment of advanced stage ION in a clinical trial. Ten patients with stage 3 ION were enrolled in this study. Autologous bone marrow-derived MSCs were cultured with autologous serum, and cells (0.5-1.0×10(8)) were transplanted after mixing with β-TCP granules in combination with vascularized iliac bone grafts. Patients were assessed 24 months after treatment. The primary and secondary endpoints were progression of the radiological stage and changes in bone volume at the femoral head, and clinical score, respectively. Nine of ten patients completed the protocol, seven of whom remained at stage 3, and the remaining two cases progressed to stage 4. The average bone volume increased from 56.5±8.5 cm(3) to 57.7±10.6 cm(3). The average clinical score according to the Japan Orthopaedic Association improved from 65.6±25.5 points to 87.9±19.0 points. One severe adverse event was observed, which was not related to the clinical trial. Although the efficacy of cell transplantation was still to be determined, all procedures were successfully performed and some young patients with extensive necrotic lesions with pain demonstrated good bone regeneration with amelioration of symptoms. Further improvements in our method using MSCs and the proper selection of patients will open a new approach for the treatment of this refractory disease.

Stem cells and biological approaches to treatment of wrist problems

Stem cells are being intensively studied for their potential applications in clinical medicine. Mesenchymal stem cells (MSCs) are an important subset of stem cells which are attractive for application in musculoskeletal disorders. In this article, we review the characteristics of these MSCs that are relevant to clinical practice but that are still largely experimental in nature.

Morphology and histology of the collapsed lunate in advanced kienböck disease

Morphological and histological changes of 24 collapsed lunates in advanced Kienböck disease were investigated. Articular cartilage of a collapsed lunate were consistently attenuated or disappeared. The proximal articular cartilage facing the radius is generally more affected than the distal articular cartilage facing the capitate. There was one major fracture in addition to multiple minor fractures in the collapsed lunate. Fracture patterns were classified into three types according to the directions of major fracture, namely horizontal type, dual oblique type, and vertical type. There were viable and necrotic areas in the collapsed lunate. Active new bone formation was observed at the junction between the viable and necrotic bone area of the collapsed lunate in advanced Kienböck disease.

The molecular chaperone Hsp47 is essential for cartilage and endochondral bone formation

Heat shock protein 47 kDa (Hsp47) is considered as a molecular chaperone essential for the correct folding of type I and type IV procollagen in the ER. However, the function of Hsp47 for other types of procollagen and its importance for chondrogenesis have never been elucidated. To examine the function of Hsp47 in cartilage formation and endochondral ossification, we conditionally inactivated the Hsp47 gene in chondrocytes using Hsp47 floxed mice and mice carrying a chondrocyte-specific Col2a1-Cre transgene. Hsp47 conditional null mutant mice died just before or shortly after birth, and exhibited severe generalized chondrodysplasia and bone deformities with lower levels of type II and type XI collagen. Second-harmonic generation (SHG) analysis and electron microscopy revealed the accumulation of misaligned type I collagen molecules in the intervertebral discs and a substantial decrease in type II collagen fibers, respectively. Whole-mount skeletal staining showed no calcified region in the vertebral bodies of sacral vertebrae, and revealed that the endochondral bones were severely twisted and shortened. These results demonstrate that Hsp47 is indispensable for well-organized cartilage and normal endochondral bone formation.

Effectiveness of bone marrow transplantation for revitalizing a severely necrotic small bone: experimental rabbit model

BACKGROUND

Although treating Kienböck disease is controversial, we previously applied a new method that was less invasive and comprised drilling, bone marrow (BM) transplantation, external fixation, and radiating low-intensity pulsed ultrasound. We reported good clinical results obtained by this new method, which were comparable to those obtained using other, rather invasive methods. Here, we investigated the effect of drilling holes and transplanting BM into necrotic bone in an animal model to further understand the effect of these methods on the revitalization of necrotic bone.

METHODS

We used rabbit fourth tarsal bones, whose surfaces consist of cartilage and cortical bone, mimicking human lunate bone. We soaked the retrieved bones in liquid nitrogen to induce necrosis. After thawing, we inserted them separately into bilateral subcutaneous pouches in the backs of rabbits. A total of 60 rabbits were divided into four groups of 15 rabbits each: BM transplantation (BM group); peripheral blood transplantation (PB group); drilling (D group); control (C group). We sacrificed three rabbits to obtain six specimens in each group at 2, 4, 8, 12, and 20 weeks after operation and evaluated the specimens histomorphologically.

RESULTS

In the BM group, significantly larger mineralizing surfaces, osteoblast surfaces, and osteoclast numbers were observed at 4, 8, and 12 weeks compared with those in the other groups. No significant differences were observed at 2 and 20 weeks in the groups except the mineralizing surface of the 20-week-BM group, which was significantly greater.

CONCLUSIONS

We examined the efficacy of drilling and of BM transplantation for regenerating necrotic bone in a rabbit model. Our experiments suggest that drilling with BM transplantation to the necrotic bone accelerates bone formation and remodeling.

Stromal cell-derived factor 1/CXCR4 signaling is critical for the recruitment of mesenchymal stem cells to the fracture site during skeletal repair in a mouse model

OBJECTIVE

Stromal cell-derived factor 1 (SDF-1; CXCL12/pre-B cell growth-stimulating factor) is a dominant chemokine in bone marrow and is known to be involved in inflammatory diseases, including rheumatoid arthritis. However, its role in bone repair remains unknown. The purpose of this study was to investigate the role of SDF-1 and its receptor, CXCR4, in bone healing.

METHODS

The expression of SDF-1 during the repair of a murine structural femoral bone graft was examined by real-time polymerase chain reaction and immunohistochemical analysis. The bone graft model was treated with anti-SDF-1 neutralizing antibody or TF14016, an antagonist for CXCR4, and evaluated by histomorphometry. The functional effect of SDF-1 on primary mesenchymal stem cells was determined by in vitro and in vivo migration assays. New bone formation in an exchanging-graft model was compared with that in the autograft models, using mice partially lacking SDF-1 (SDF-1(+/-)) or CXCR4 (CXCR4(+/-)).

RESULTS

The expression of SDF1 messenger RNA was increased during the healing of live bone grafts but was not increased in dead grafts. High expression of SDF-1 protein was observed in the periosteum of the live graft. New bone formation was inhibited by the administration of anti-SDF-1 antibody or TF14016. SDF-1 increased mesenchymal stem cell chemotaxis in vitro in a dose-dependent manner. The in vivo migration study demonstrated that mesenchymal stem cells recruited by SDF-1 participate in endochondral bone repair. Bone formation was decreased in SDF-1(+/-) and CXCR4(+/-) mice and was restored by the graft bones from CXCR4(+/-) mice transplanted into the SDF-1(+/-) femur, but not vice versa.

CONCLUSION

SDF-1 is induced in the periosteum of injured bone and promotes endochondral bone repair by recruiting mesenchymal stem cells to the site of injury.

Secretion of angiogenic proteins by human multipotent mesenchymal stromal cells and their clinical potential in the treatment of avascular osteonecrosis

Osteonecrosis is a frequent complication after treatment for childhood leukemia and other steroid-based therapies. The success rate of core decompression surgery is limited. Therefore, we evaluated relevant biological characteristics of human multipotent mesenchymal stromal cells (MSCs) in vitro. MSCs cultured under low-oxygen tensions showed decreased proliferation and differentiation into bone. However, these MSCs secreted significant amounts of vascular endothelial-derived factor in the presence of interferon-gamma. These in vitro results with potential effects on neovascularization and bone regeneration as well as findings in animal models prompted us to treat five patients with steroid-induced osteonecrosis of the femur by core decompression surgery and instillation of expanded autologous MSCs. Within 3 weeks of culture, sufficient numbers of MSCs were generated using animal protein-free culture conditions. No chromosomal aberrations were detected by matrix-based comparative genomic hybridization. Application of MSCs during core decompression was feasible and safe. Median follow-up is 16 months and the patients in this pilot study reported clinical improvement. Formation of mineralized bone in the osteonecrotic cavity was proven by computed tomography. Taken together, MSCs display biological properties that may add to the efficiency of surgical treatment in osteonecrosis and should be evaluated in larger patient cohorts.