Isolation and characterization of myogenic precursor cells from human cremaster muscle.

Human myogenic precursor cells have been isolated and expanded from a number of skeletal muscles, but alternative donor biopsy sites must be sought after in diseases where muscle damage is widespread. Biopsy sites must be relatively accessible, and the biopsied muscle dispensable. Here, we aimed to histologically characterize the cremaster muscle with regard number of satellite cells and regenerative fibres, and to isolate and characterize human cremaster muscle-derived stem/precursor cells in adult male donors with the objective of characterizing this muscle as a novel source of myogenic precursor cells. Cremaster muscle biopsies (or adjacent non-muscle tissue for negative controls; N = 19) were taken from male patients undergoing routine surgery for urogenital pathology. Myosphere cultures were derived and tested for their in vitro and in vivo myogenic differentiation and muscle regeneration capacities. Cremaster-derived myogenic precursor cells were maintained by myosphere culture and efficiently differentiated to myotubes in adhesion culture. Upon transplantation to an immunocompromised mouse model of cardiotoxin-induced acute muscle damage, human cremaster-derived myogenic precursor cells survived to the transplants and contributed to muscle regeneration. These precursors are a good candidate for cell therapy approaches of skeletal muscle. Due to their location and developmental origin, we propose that they might be best suited for regeneration of the rhabdosphincter in patients undergoing stress urinary incontinence after radical prostatectomy.

Effect of bone marrow stromal cells in combination with biomaterials in early phases of distraction osteogenesis: An experimental study in a rabbit femur model.

Acceleration of the consolidation of the distracted bone is a relevant medical need. As a platform to improve in vivo bone engineering, we developed a novel distraction osteogenesis (DO) model in a rabbit large bone (femur) and tested if the application of cultured bone marrow stromal cells (BMSCs) immediately after the osteotomy promotes the formation of bone. This report consists of two components, an animal study to evaluate the quality of the regenerate following different treatments and an in vitro study to evaluate osteogenic potential of BMSC cultures. To illuminate the mechanism of action of injected cells, we tested stem cell cultures enriched in osteogenic-BMSCs (O-BMSCs) as compared with cultures enriched in non-osteogenic BMSCs (NO-BMSCs). Finally, we included a group of animals treated with biomaterials (fibrin and ground cortical bone) in addition to cells. Injection of O-BMSCs promoted the maturity of distracted callus and decreased fibrosis. When combined with biomaterials, O-BMSCs modified the ossification pattern from endochondral to intramembranous type. The use of NO-BMSCs not only did not increase the maturity but also increased porosity of the bone. These preclinical results indicate that the BMSC cultures must be tested in vitro prior to clinical use, since a number of factors may influence their outcome in bone formation. We hypothesize that the use of osteogenic BMSCs and biomaterials could be clinically beneficial to shorten the consolidation period of the distraction and the total period of bone lengthening.

A pilot clinical study of hair grafting in chronic leg ulcers.

Epidermal sheets spread centrifugally postinjury from the hair follicle infundibulum to reepithelialize the wound bed. Healing progresses faster in skin areas rich in terminal hair follicles. These observations are consistent with the role of the hair follicle as a major reservoir for progenitor cells. To evaluate the feasibility and potential healing capacity of autologous scalp follicular grafts transplanted into the wound bed of chronic leg ulcers, 10 patients with ulcers of an average 36.8 cm(2) size and a 10.5-year duration were included in this pilot study. Within each ulcer we randomly assigned a 2 × 2 cm "experimental" square to receive 20 hair grafts and a nongrafted "control" square of equal size. The procedure seemed to be safe, although major unrelated complications occurred in two patients. At the 18-week end point, we observed a 27.1% ulcer area reduction in the experimental square as compared with 6.5% in the control square (p = 0.046) with a maximum 33.5% vs. 9.7% reduction at week 4 (p = 0.007). Histological analyses showed enhanced epithelialization, neovascularization, and dermal reorganization. We conclude that terminal hair follicle grafting into wound beds is feasible in an outpatient setting and represents a promising therapeutic alternative for nonhealing chronic leg ulcers.

Age-dependent depletion of human skin-derived progenitor cells.

A major unanswered question in autologous cell therapy is the appropriate timing for cell isolation. Many of the putative target diseases arise with old age and previous evidence, mainly from animal models, suggests that the stem/progenitor cell pool decreases steadily with age. Studies with human cells have been generally hampered to date by poor sample availability. In recent years, several laboratories have reported on the existence, both in rodents and humans, of skin-derived precursor (SKP) cells with the capacity to generate neural and mesodermal progenies. This easily obtainable multipotent cell population has raised expectations for their potential use in cell therapy of neurodegeneration. However, we still lack a clear understanding of the spatiotemporal abundance and phenotype of human SKPs. Here we show an analysis of human SKP abundance and in vitro differentiation potential, by using SKPs isolated from four distinct anatomic sites (abdomen, breast, foreskin, and scalp) from 102 healthy subjects aged 8 months to 85 years. Human SKP abundance and differentiation potential decrease sharply with age, being extremely difficult to isolate, expand, and differentiate when obtained from the elderly. Our data suggest preserving human SKP cell banks early in life would be desirable for use in clinical protocols in the aging population.