Heat-Shock Proteins Can Potentiate the Therapeutic Ability of Cryopreserved Mesenchymal Stem Cells for the Treatment of Acute Spinal Cord Injury in Dogs

Abstract

Background Mesenchymal stem cells (MSCs) are applied in the treatment of spinal cord injury (SCI) because of their neural tissue restoring ability. In the clinical setting, intravenous injection of cryopreserved cells is essential for the immediate treatment of SCI, exhibiting the disadvantage of reduced cell properties. Methods In this study, we potentiated the characteristics of cryopreserved MSCs by heat-shock (HS) treatment to induce the expression of HS protein (HSP) HSP70/HSP27 and further improved antioxidant capacity by overexpressing HSP32 (heme oxygenase-1 [HO-1]). We randomly assigned 12 beagle dogs with acute SCI into three groups and transplanted cells intravenously: (i) F-MSCs (MSCs in frozen/thawed conditions); (ii) F-HSP-MSCs (HS-treated MSCs in frozen/thawed conditions); and (iii) F-HSP-HO-MSCs (HO-1-overexpressing and HS-treated MSCs in frozen/thawed conditions). Results The potentiated MSCs exhibited increased growth factor-, anti-inflammatory-, antioxidant-, homing- and stemness-related gene expression. In the animal experiments, the HSP-induced groups showed significant improvement in hind-limb locomotion, highly expressed neural markers, less intervened fibrotic changes, and improved myelination. In particular, the HO-1-overexpression group was more prominent, controlling the initial inflammatory response with high antioxidant capabilities, suggesting that antioxidation was important to prevent secondary injury. Accordingly, HSPs not only successfully increased the ability of frozen MSCs but also demonstrated excellent neural protection and regeneration capacity in the case of acute SCI. Conclusions The application of HSP-induced cryopreserved MSCs in first- aid treatment for acute SCI is considered to help early neural sparing and further hind-limb motor function restoration.