Amniotic Fluid Stem Cells Restore the Muscle Cell Niche in a HSA‐Cre , Smn ^F7/F7 Mouse Model

Abstract

Mutations in the survival of motor neuron gene (SMN1) are responsible for spinal muscular atrophy, a fatal neuromuscular disorder. Mice carrying a homozygous deletion of Smn exon 7 directed to skeletal muscle (HSA-Cre, Smn F7/F7 mice) present clinical features of human muscular dystrophies for which new therapeutic approaches are highly warranted. Herein we demonstrate that tail vein transplantation of mouse amniotic fluid stem (AFS) cells enhances the muscle strength and improves the survival rate of the affected animals. Second, after cardiotoxin injury of the Tibialis Anterior, only AFS-transplanted mice efficiently regenerate. Most importantly, secondary transplants of satellite cells (SCs) derived from treated mice show that AFS cells integrate into the muscle stem cell compartment and have long-term muscle regeneration capacity indistinguishable from that of wild-type-derived SC. This is the first study demonstrating the functional and stable integration of AFS cells into the skeletal muscle, highlighting their value as cell source for the treatment of muscular dystrophies.

CD117+amniotic fluid stem cells

“…The authors hypothesized that undifferentiated AFS cells first migrated into the regenerating myofibers driven by cytokines or chemokines, then converted into myogenic precursors residing in the satellite cell niche as demonstrated by Myf-5 expression, and finally were activated to fuse with the myofibers. Very recently, Piccoli et al 44 demonstrated for the first time the functional and stable long-term integration of AFS cells into the skeletal muscle of HSA-Cre Smn F7/F7 mutant mice, which closely replicate the clinical features of human muscular dystrophies. AFS cells were obtained from E11.5-13.…”

“…35,37,43 In a single study, murine AFS cells have been also successfully cultured onto feeder layers (i.e., mitomycin C-treated mouse embryonic fibroblasts) in basic medium supplemented with 15% fetal bovine serum, mercaptoethanol, stem cell factor (SCF), bone morphogenetic protein 4 (BMP4) and leukemia inhibitory factor (LIF). 44 Whether, these different culture protocols influence AFS cell features and potential remains to be established.…”

“…42,46 Second trimester human AFS cells or rodent cells of equivalent gestational age have been employed in all cases; to our knowledge, no data resulting from the administration of 1st trimester AFS cells or reprogrammed AFiPS cells are currently available. In the majority of the existing studies AFS cells have been utilized after previous expansion in culture; only in the works by Ditadi et al 37 and Piccoli et al 44 the cells were administered in vivo immediately after isolation from the AF without any passage in vitro.…”

Immune Regulatory Properties of CD117pos Amniotic Fluid Stem Cells Vary According to Gestational Age

“…Both first and second trimester-derived AFS cells revert to a functional pluripotent state when cultured in small molecule cocktail, that is, chemically induced pluripotent stem cells [8,9]. Furthermore, AFS cells cross the endothelial barrier after systemic injection, thus engrafting into injured tissues [10][11][12][13].…”

“…The therapeutic efficacy of AFS cells has been recently verified in in vivo preclinical studies showing their capabilities to regenerate and improve the functionality of injured tissues and to restore cell niche homeostasis in muscle, bone, lung, and kidney [10,[13][14][15][16]. In addition and similar to MSCs-an already thoroughly characterized immune regulatory cell type [17], AFS cells possess significant immune modulatory properties, as they may both suppress in vitro inflammatory responses, mainly through soluble factors [18], and modulate in vivo cellular immune response and distant organ damage during sublethal endotoxemia in animal models [19].…”