Transplantation of Human Skin-Derived Mesenchymal Stromal Cells Improves Locomotor Recovery After Spinal Cord Injury in Rats

Abstract

Spinal cord injury (SCI) is a devastating neurologic disorder with significant impacts on quality of life, life expectancy, and economic burden. Although there are no fully restorative treatments yet available, several animal and small-scale clinical studies have highlighted the therapeutic potential of cellular interventions for SCI. Mesenchymal stem cells (MSCs)-which are conventionally isolated from the bone marrow-recently emerged as promising candidates for treating SCI and have been shown to provide trophic support, ameliorate inflammatory responses, and reduce cell death following the mechanical trauma. Here we evaluated the human skin as an alternative source of adult MSCs suitable for autologous cell transplantation strategies for SCI. We showed that human skin-derived MSCs (hSD-MSCs) express a range of neural markers under standard culture conditions and are able to survive and respond to neurogenic stimulation in vitro. In addition, using histological analysis and behavioral assessment, we demonstrated as a proof-of-principle that hSD-MSC transplantation reduces the severity of tissue loss and facilitates locomotor recovery in a rat model of SCI. Altogether, the study provides further characterization of skin-derived MSC cultures and indicates that the human skin may represent an attractive source for cell-based therapies for SCI and other neurological disorders. Further investigation is needed to elucidate the mechanisms by which hSD-MSCs elicit tissue repair and/or locomotor recovery.

Keywords: Cell transplantation; Human skin; Mesenchymal stem cells; Spinal cord injury.

Fig. 1

Characterization of human skin-derived mesenchymal stromal cell (hSD-MSC) cultures. a Phase photomicrograph microscopy of SD-MSCs displaying plastic adhesion ability and fibroblast-like morphology. Cells cultured in specific inductive media produced b Oil red O-stained lipid vesicles and c Alizarin Red-stained mineralized nodules. Scale bar 200 μm. d Flow cytometry analysis for hematopoietic (CD34 and CD45) and mesenchymal (CD73, CD90, and CD105) stem cell surface markers. Red curves represent the specific markers, and blue curves represent the negative controls. Immunofluorescent staining for the neural lineage markers e βIII-tubulin, f NF-M, g NSE, h GFAP, i Nestin, and j p75NTR. Representative images of three independent experiments. Scale bar 200 μm (Color figure online)

Fig. 2

In vitro neurogenic stimulation of hSD-MSCs. Cells were cultured in neuronal inductive medium or in standard medium supplemented with EGF-FGF2 (see “Materials and Methods” section) and subjected to immunofluorescent analysis. Representative images of positive cells stained for a NSE, b NF-M, c ASCL1, and d MAP2. e Percentage of positive cells in relation to the total cell number in the different culture conditions. Values are expressed as mean ± S.E.M of 20 random fields in three independent experiments. *P < 0.05 and ***P < 0.001 (One-way ANOVA). Scale bar 200 μm

Fig. 3

Acute transplantation of human SD-MSC improves locomotor recovery and reduces tissue loss after SCI. a BBB scoring for locomotor function assessed every 5 days up to 60 days post-trauma. Values represent the mean ± S.E.M. of 5–7 animals for each group. * P < 0.05 by repeated measures ANOVA. b Representative longitudinal spinal cord sections stained with hematoxilyn-eosin from the indicated groups. c Quantification of of tissue loss (atrophy areas) at day 60. *P < 0.05 and **P (One-way ANOVA). Scale bar 500 μm