Exosomes secreted from sonic hedgehog-modified bone mesenchymal stem cells facilitate the repair of rat spinal cord injuries

Abstract

Background Spinal cord injuries (SCIs) can cause a loss of neurons and associated sensory and motor functionality below the injured site. No approaches to treating SCIs in humans have been developed to date. Exosomes are extracellular vesicles that hold promise as a potential therapeutic modality when treating such injuries. The present study was thus designed to determine whether sonic hedgehog (Shh)-overexpressing bone mesenchymal stem cell (BMSC)-derived exosomes were protective in the context of SCIs. Methods Exosomes were extracted from control or Shh lentivirus-transduced BMSCs, yielding respective BMSC-Exo and BMSC-Shh-Exo preparations which were intravenously injected into SCI model rats. Shh expression in spinal cord tissues in these animals was then assessed via immunohistochemical staining, while Basso-Beattie-Bresnahan (BBB) scores were utilized to measure high limb motor function. Neuronal damage and regeneration within the spinal cord were additionally evaluated via terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), Nissl, hematoxylin and eosin, and immunofluorescent staining. Results Both BMSC-Exo and BMSC-Shh-Exo preparations significantly increased Shh expression in the spinal cord of SCI model rats and improved BBB scores in these treated animals, while also increasing the frequencies of Nissl- and NeuN-positive neurons are reducing the numbers of apoptotic and GFAP-positive neurons. While both treatments yielded some degree of benefit to treated animals relative to untreated controls, BMSC-Shh-Exos were more beneficial than were control BMSC-Exos. Conclusions Shh-overexpressing BMSC-derived exosomes represent an effective treatment that can facilitate SCI repair in rats.

Development of Extracellular Vesicle Therapeutics: Challenges, Considerations, and Opportunities

“…Further, the capacity of EVs to transfer biological and pharmaceutical molecules to specific tissues and cell types has raised considerable interest in their development as biocompatible drug delivery systems [reviewed in Sluijter et al (2018) ; Pirisinu et al (2020) ; Herrmann et al (2021) ; and Rankin-Turner et al (2021) ]. At present, https://www.clinicaltrials.gov lists 224 studies which include “exosome,” 84 with “extracellular vesicle,” 9 with “nanocarrier,” 4 with “engineered exosome,” and 2,101 with “liposome.” While a portion of these are diagnostic/biomarker studies, most are clinical trials based on pre-clinical therapeutic success in wound healing (NCT04761562, NCT04281901, and NCT04664738) ( Jia et al, 2021 ; Zhao et al, 2021 ), heart disease (NCT04327635) ( Aday et al, 2021 ; Hu S. et al, 2021 ), COVID-19 (NCT04657458, NCT04493242, NCT04276987, NCT04747574, NCT04389385, and NCT04969172) ( Mitrani et al, 2021 ), infectious disease (NCT01478347, NCT01717638, and NCT04350138), diabetes (NCT02138331), stroke (NCT03384433), arthritis (NCT04223622), and drug delivery (NCT01294072, NCT02889822, and NCT04217096). While classified as EV therapies, such studies are more often comprised of a variety of secreted components (i.e., secretome containing soluble factors and EVs) than purified EVs ( Table 1 ).…”

“…There are now clinical trials further evaluating the safety and efficacy of this treatment for COVID-19 (NCT04384445, NCT04657406). Another major application of EV therapies is in accelerated and improved healing and regeneration of damaged tissue ( Dalirfardouei et al, 2021 ; Hu S. et al, 2021 ; Jia et al, 2021 ; Lou et al, 2021 ; Saludas et al, 2021 ; Zhao et al, 2021 ). There are promising results in the utilization of EVs to repair arthritic joints (NCT04223622) ( Cosenza et al, 2017 ; Wang et al, 2017 ; Wu et al, 2019 ; Zhang S. et al, 2019 ; Jin et al, 2020 ) and spinal-cord injuries ( Rong et al, 2019 ; Li L. et al, 2020 ; Jia et al, 2021 ), with tissue restoration in EV treatments exceeding that of untreated animals/tissue.…”

“…Significant changes in the FDA (Critical Path Initiative) now support development of patient screens to improve the chances for drug approval, and integration of pharmacogenomic data (proteomics, metabolomics, genome-wide association study data) in developing and evaluating medicines. In the context of EV-based therapeutics, identification of active components as a constituent of the total EV will enable optimization and improvements in dosing and effect ( Xin et al, 2017 ; Jia et al, 2021 ).…”

“…Frontiers in Cell and Developmental Biology | www.frontiersin.org Hu S. et al, 2021;Jia et al, 2021;Lou et al, 2021;Saludas et al, 2021;Zhao et al, 2021). There are promising results in the utilization of EVs to repair arthritic joints (NCT04223622) (Cosenza et al, 2017;Wu et al, 2019;Zhang S. et al, 2019;Jin et al, 2020) and spinal-cord injuries (Rong et al, 2019;Li L. et al, 2020;Jia et al, 2021), with tissue restoration in EV treatments exceeding that of untreated animals/tissue. As these are recent developments, mechanism of action and clinical translation are still underway.…”

Repair of spinal cord injury in rats via exosomes from bone mesenchymal stem cells requires sonic hedgehog

“…Besides, activated Shh signaling pathway was found to promote recovery from SCI in a rat model [ 17 ]. Our prior study found that Shh-overexpressing BMSC-derived exosomes can facilitate SCI repair in rats [ 18 ]. However, whether Shh is necessary for BMSC-derived exosomes to augment SCI repair is yet to be studied.…”