Exploration of the optimal retention method in vivo for stem cell therapy: Low-intensity ultrasound preconditioning

Abstract

Bone marrow mesenchymal stem cells (BMSCs) are pluripotent and self-renewing, exerting a crucial role in the domain of regenerative medicine. Nevertheless, BMSCs encounter challenges such as low cell viability and inadequate homing during transplantation, thereby restricting their therapeutic efficacy. Hence, current research is concentrated on identifying optimal retention approaches following BMSCs transplantation to enhance its effectiveness. Low-intensity ultrasound (LIUS) has been verified as an efficacious method to enhance the performance of BMSCs. We established a skin trauma model and assessed the therapeutic effect of LIUS-preconditioned BMSCs. The results demonstrated that pretreatment with LIUS could expedite wound healing and effectively diminish scar formation post-transplantation by promoting proliferation capacity, reinforcing anti-apoptotic attributes, improving homing ability, and significantly enhancing the transplantation effect of BMSCs. These discoveries imply that LIUS might constitute a promising strategy for attaining optimal retention after stem cell transplantation in regenerative medicine and wound repair therapy.

Keywords: Apoptosis; Bone marrow mesenchymal stem cells; Low-intensity ultrasound; Optimal retention method; Preconditioning.

Fig. 1

The flow chart of the in vivo experiment.

Fig. 2

A. The healing of skin wounds in each group of rats. B. The days of skin wound healing in each group. C. Scar area after skin wound healing in each group. D. The H&E staining of skin lesions in inflammatory and proliferative phases in each group (×100, ×200). E. Comparison of the amount of neovascularization in inflammatory and proliferative phases of skin lesions in each group. F. The H&E staining of skin lesions in the remodeling phase in each group (×100, ×200). G. Comparison of epidermal thickness index in remodeling phase of skin lesions in each group. H. The Masson staining of skin lesions in the remodeling phase in each group (×100, ×400). I. Comparison of percentage of collagen volume in the remodeling stage of skin lesions in each group. ∗P < 0.05; ∗∗P < 0.01.

Fig. 3

A. The proliferative activity of BMSCs was detected by MTT. B. The effect of LIUS on the apoptosis rate of BMSCs was detected by flow cytometry. C–D. Detection of the mitochondrial membrane potential of BMSCs in each group by JC-1 staining (×200). E–F. Fluo-3 fluorescent staining was used to detect the intracellular calcium concentration in the LIUS group and Control group. ∗P < 0.05; ∗∗P < 0.01.

Fig. 4

A. The TUNEL detection of apoptosis of skin lesions in the proliferative phase in each group (×400). B. Comparison of apoptosis index in each group. C–H. Immunohistochemical detection of Caspase-3, Bax, and Bcl-2 expression of skin lesions in the proliferative phase in each group (×400). I–J. Comparison of relative expression of Bax and Bcl-2-related mRNA in the proliferative phase of skin lesions in each group. K–L. Comparison of serum TNF-α and PDGF levels in each group. ∗P < 0.05; ∗∗P < 0.01.

Fig. 5

A. Fluorescent CD90 labelling of BMSCs and distribution in skin tissues in each group. B. Green fluorescence density of CD90 in each group. C. Comparison of serum SDF-1 levels in each group. D. The morphology of BMSCs after LIUS irradiation was observed under optical microscope (×40). ∗P < 0.05; ∗∗P < 0.01; ∗∗∗∗P < 0.0001.

Fig. 6

A. The volcano map of DEGs. B. The clustering heat map of DEGs. C. The GO enrichment analysis (biological process) of DEGs. D. The KEGG enrichment analysis of the DEGs.