Chimeric Cells of Myoblast Origin as a Novel Stem Cell Based Therapy for Duchenne Muscular Dystrophy

Siemionow M, Cwykiel J, Heydemann A, et al. Dystrophin Expressing Chimeric (DEC) Human Cells Provide a Potential Therapy for Duchenne Muscular Dystrophy. Stem cell reviews 2018;14:370-384.

Siemionow M, Cwykiel J, Heydemann A, Garcia-Martinez J, Siemionow K, Szilagyi E. Creation of Dystrophin Expressing Chimeric Cells of Myoblast Origin as a Novel Stem Cell Based Therapy for Duchenne Muscular Dystrophy. Stem cell reviews 2018;14:189-199.

Siemionow_2018_Stem Cell Rev. Apr;14(2);189-199

Siemionow_2018_Stem Cell Rev. Jun;14(3);370-384

Studies into stem cells (cells that still have the ability to become different kinds of cells, e.g. muscle cells) that produce the missing dystrophin protein, have so far not been very effective. One of the problems is that the cells elicited are broken down by the immune system. This group produced a new type of stem cells, which are a combination of the cells found in DMD (which do not produce dystrophin) and dystrophin expressing stem cells. Hereby they hope to prevent an immune reaction. First they tested murine cells in the DMD mouse model. Thereafter human cells were tested in a DMD mouse model, which has a low immune response, since the human cells will otherwise be rejected. In both cases newly formed dystrophin protein was seen and the muscle function was improved. So far, this has only yet been tested in mice.

 

Abstracts

Over the past decade different stem cell (SC) based approaches were tested to treat Duchenne Muscular Dystrophy (DMD), a lethal X-linked disorder caused by mutations in dystrophin gene. Despite research efforts, there is no curative therapy for DMD. Allogeneic SC therapies aim to restore dystrophin in the affected muscles; however, they are challenged by rejection and limited engraftment. Thus, there is a need to develop new more efficacious SC therapies. Chimeric Cells (CC), created via ex vivo fusion of donor and recipient cells, represent a promising therapeutic option for tissue regeneration and Vascularized Composite Allotransplantation (VCA) due to tolerogenic properties that eliminate the need for lifelong immunosuppression. This proof of concept study tested feasibility of myoblast fusion for Dystrophin Expressing. Chimeric Cell (DEC) therapy through in vitro characterization and in vivo assessment of engraftment, survival, and efficacy in the mdx mouse model of DMD. Murine DEC were created via ex vivo fusion of normal (snj) and dystrophin-deficient (mdx) myoblasts using polyethylene glycol. Efficacy of myoblast fusion was confirmed by flow cytometry and dystrophin immunostaining, while proliferative and myogenic differentiation capacity of DEC were assessed in vitro. Therapeutic effect after DEC transplant (0.5 x 10(6)) into the gastrocnemius muscle (GM) of mdx mice was assessed by muscle functional tests. At 30 days post-transplant dystrophin expression in GM of injected mdx mice increased to 37.27 +/- 12.1% and correlated with improvement of muscle strength and function. Our study confirmed feasibility and efficacy of DEC therapy and represents a novel SC based approach for treatment of muscular dystrophies.

Duchenne Muscular Dystrophy (DMD) is a progressive and lethal disease caused by mutations of the dystrophin gene. Currently no cure exists. Stem cell therapies targeting DMD are challenged by limited engraftment and rejection despite the use of immunosuppression. There is an urgent need to introduce new stem cell-based therapies that exhibit low allogenic profiles and improved cell engraftment. In this proof-of-concept study, we develop and test a new human stem cell-based approach to increase engraftment, limit rejection, and restore dystrophin expression in the mdx/scid mouse model of DMD. We introduce two Dystrophin Expressing Chimeric (DEC) cell lines created by ex vivo fusion of human myoblasts (MB) derived from two normal donors (MB(N1)/MB(N2)), and normal and DMD donors (MB(N)/MB(DMD)). The efficacy of fusion was confirmed by flow cytometry and confocal microscopy based on donor cell fluorescent labeling (PKH26/PKH67). In vitro, DEC displayed phenotype and genotype of donor parent cells, expressed dystrophin, and maintained proliferation and myogenic differentiation. In vivo, local delivery of both DEC lines (0.5 x 10(6)) restored dystrophin expression (17.27%+/-8.05-MB(N1)/MB(N2) and 23.79%+/-3.82-MB(N)/MB(DMD)) which correlated with significant improvement of muscle force, contraction and tolerance to fatigue at 90 days after DEC transplant to the gastrocnemius muscles (GM) of dystrophin-deficient mdx/scid mice. This study establishes DEC as a potential therapy for DMD and other types of muscular dystrophies.

 

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