Contribution of Human Muscle-Derived Cells to Skeletal Muscle Regeneration in Dystrophic Host Mice

Abstract

BackgroundStem cell transplantation is a promising potential therapy for muscular dystrophies, but for this purpose, the cells need to be systemically-deliverable, give rise to many muscle fibres and functionally reconstitute the satellite cell niche in the majority of the patient's skeletal muscles. Human skeletal muscle-derived pericytes have been shown to form muscle fibres after intra-arterial transplantation in dystrophin-deficient host mice. Our aim was to replicate and extend these promising findings.Methodology/Principal FindingsIsolation and maintenance of human muscle derived cells (mdcs) was performed as published for human pericytes. Mdscs were characterized by immunostaining, flow cytometry and RT-PCR; also, their ability to differentiate into myotubes in vitro and into muscle fibres in vivo was assayed. Despite minor differences between human mdcs and pericytes, mdscs contributed to muscle regeneration after intra-muscular injection in mdx nu/nu mice, the CD56+ sub-population being especially myogenic. However, in contrast to human pericytes delivered intra-arterially in mdx SCID hosts, mdscs did not contribute to muscle regeneration after systemic delivery in mdx nu/nu hosts.Conclusions/SignificanceOur data complement and extend previous findings on human skeletal muscle-derived stem cells, and clearly indicate that further work is necessary to prepare pure cell populations from skeletal muscle that maintain their phenotype in culture and make a robust contribution to skeletal muscle regeneration after systemic delivery in dystrophic mouse models. Small differences in protocols, animal models or outcome measurements may be the reason for differences between our findings and previous data, but nonetheless underline the need for more detailed studies on muscle-derived stem cells and independent replication of results before use of such cells in clinical trials.

Human skeletal muscle fibroblasts, but not myogenic cells, readily undergo adipogenic differentiation

“…Endothelial and haematopoietic cells do not give rise to adipocytes (Berry and Rodeheffer, 2013), and our cell counts showed that the CD56 2 / TE-7 2 population of cells (which might include these cells) is also far too small to account for the number of adipocytes observed in our cultures. The non-adherent nature of some of these cell types also ensures they would have been discarded before obtaining the sorted cells -this applies to the 'small refractory' cell population identified by Meng and co-workers (Meng et al, 2011), the 'muscle-derived stem cells' (Lee et al, 2000;Qu-Petersen et al, 2002) and the pericytes identified in human muscle by Dellavalle and colleagues (Dellavalle et al, 2011). The small refractory cells (Meng et al, 2011) were initially both CD56 2 and non-adherent; only after 14 days in culture and when provided with collagen-I substrate were they able to adhere, and eventually gave rise to some CD56 + cells.…”

“…The non-adherent nature of some of these cell types also ensures they would have been discarded before obtaining the sorted cells -this applies to the 'small refractory' cell population identified by Meng and co-workers (Meng et al, 2011), the 'muscle-derived stem cells' (Lee et al, 2000;Qu-Petersen et al, 2002) and the pericytes identified in human muscle by Dellavalle and colleagues (Dellavalle et al, 2011). The small refractory cells (Meng et al, 2011) were initially both CD56 2 and non-adherent; only after 14 days in culture and when provided with collagen-I substrate were they able to adhere, and eventually gave rise to some CD56 + cells. The 'muscle-derived stem cells' obtained by Lee and co-workers (Lee et al, 2000), could only be obtained by repeated subculturing of non-adherent cells, and the CD56 2 'pericytes' with multi-lineage potential that were identified in human muscle (Dellavalle et al, 2011) are also a small fraction (estimated at about 2-4% of the isolated cell population).…”

Stem Cell Based Therapy for Muscular Dystrophies: Cell Types and Environmental Factors Influencing Their Efficacy

“…within muscle fibers and/or satellite cells. But CD56 -or non-sorted cells contributed to significantly more nuclei outside the basal lamina, confirming that there were more non-myogenic cells within CD56 -cell population (Meng et al, 2011b). Zheng et al showed that human skeletal muscle-derived CD56 + cells that also expressed CD34 and CD144 (myoendothelial cells) contributed to more muscle regeneration than did CD56 + /CD34 -/CD144 -cells (myoblasts) (Zheng et al, 2007) in contrast to the findings of Meng suggesting that pericytes, rather than endothelial cells, are the major CD56 -contributor to muscle regeneration (Meng et al, 2011b) …”

“…However, when grafting cells from one donor to another, the host must either be immunodeficient or immunosuppressed. Therefore, mdx mice with different types of immunodeficiency have been used as hosts in cell transplantation experiments, including mdx nu/nu (Boldrin et al, 2009;Collins et al, 2005;Partridge et al, 1989), SCID mdx (Benchaouir et al, 2007;Dellavalle et al, 2007;Torrente et al, 2004), Rag -/-mdx (Gerard et al, 2011), or mdx mice immunosuppressed with FK506 (Kinoshita et al, 1994b), but to what extent these different hosts are comparable, being on different genetic backgrounds and having different mechanisms and degrees of immunodeficiency, has not been ascertained (reviewed (Meng et al, 2011b)). Immunodeficient mice are more convenient to work with than mice that have to be immunosuppressed and seem to permit greater donor-myoblast-derived muscle regeneration (Partridge et al, 1989).…”

“…The contribution of blood vessel-derived cells (both from skeletal muscle and embryonic dorsal aorta) to skeletal muscle regeneration in vivo after their systemic delivery has been demonstrated in several publications (Dellavalle et al, 2007;Sampaolesi et al, 2003;Sampaolesi et al, 2006)(reviewed (Sancricca et al, 2010)), however these promising findings could not be replicated by others (Meng et al, 2011b). For long-term efficacy, it would be useful to know whether a grafted pericyte self-renews to give more functional pericytes and if so, what contribution these have to further muscle regeneration.…”