Widespread Distribution and Muscle Differentiation of Human Fetal Mesenchymal Stem Cells After Intrauterine Transplantation in Dystrophic mdx Mouse

Abstract

Duchenne muscular dystrophy (DMD) is a common X-linked disease resulting from the absence of dystrophin in muscle. Affected boys suffer from incurable progressive muscle weakness, leading to premature death. Stem cell transplantation may be curative, but is hampered by the need for systemic delivery and immune rejection. To address these barriers to stem cell therapy in DMD, we investigated a fetal-to-fetal transplantation strategy. We investigated intramuscular, intravascular, and intraperitoneal delivery of human fetal mesenchymal stem cells (hfMSCs) into embryonic day (E) 14 -16 MF1 mice to determine the most appropriate route for systemic delivery. Intramuscular injections resulted in local engraftment, whereas both intraperitoneal and intravascular delivery led to systemic spread. However, intravascular delivery led to unexpected demise of transplanted mice. Transplantation of hfMSCs into E14 -16 mdx mice resulted in widespread long-term engraftment (19 weeks) in multiple organs, with a predilection for muscle compared with nonmuscle tissues (0.71% vs. 0.15%, p < .01), and evidence of myogenic differentiation of hfMSCs in skeletal and myocardial muscle. This is the first report of intrauterine transplantation of ontologically relevant hfMSCs into fully immunocompetent dystrophic fetal mice, with systemic spread across endothelial barriers leading to widespread long-term engraftment in multiple organ compartments. Although the low-level of chimerism achieved is not curative for DMD, this approach may be useful in other severe mesenchymal or enzyme deficiency syndromes, where low-level protein expression may ameliorate disease pathology. STEM CELLS 2007;25:875-884 Disclosure of potential conflicts of interest is found at the end of this article.

Fetal Microchimeric Cells in a Fetus-Treats-Its-Mother Paradigm Do Not Contribute to Dystrophin Production in Serially ParousmdxFemales

“…Although we successfully found FMCs expressing the mesenchymal marker, vimentin, they were probably too few in proportion (3/ 12 FMCs) to have a significant influence on muscle pathology. Even 0.7% engraftment of fetal MSCs after intrauterine transplantation did not ameliorate disease severity in mdx [17]. Moreover, we did not find FMCs robustly expressing proteins associated with muscle differentiation or integration.…”

“…The commonest, Duchenne muscular dystrophy, is associated with mutations in the dystrophin gene, which encodes a protein integral to muscle fiber stability [16]. In the main mouse model of Duchenne muscular dystrophy (mdx), transplantation of various stem cell populations has shown therapeutic promise [17][18][19]. Muscle-resident stem cells or satellite cells have been obvious therapeutic candidates for muscular dystrophies [20], as they are activated during normal muscle repair [20,21].…”

“…Progenitors from distal sites such as bone marrow can also repair damaged muscles, although their contribution to repair is relatively small in comparison to the resident satellite cell population. We have previously shown that human fetal mesenchymal stem cells (MSCs) delivered to mdx fetuses in utero systemically engraft all muscle tissues displaying myogenic differentiation [17]. Moreover, allogeneic bone marrow transplant recipients have small numbers of muscle fibers that contain the donor nuclei [18,22].…”

Fetal Liver-Derived Mesenchymal Stem Cell Engraftment After Allogeneic In Utero Transplantation into Rabbits

“…We [23] and others [22] have previously reported that fl-MSC possess at least some of the immunomodulatory properties found in adult-derived MSCs. In addition MSCs and, particularly, fetal MSCs are efficiently transduced with integrating vectors and express the corresponding transgene without losing stemness and differentiation capabilities [12,23,33].…”

“…Thus, human MSCs from several sources have been shown to reconstitute different tissues after human-sheep [9][10][11], human-mouse [12,13], or human-rat [14] xenogeneic in utero transplantation. Furthermore, proof-of-principle studies have recently stressed the therapeutic potential of human fetal MSCs for the treatment of severe osteogenesis imperfecta both after xenogeneic transplantation into the corresponding mouse model [15], and after allogeneic transplantation in an immunocompetent, HLA-incompatible patient [16].…”