Beneficial Effects of Transplanted Human Bone Marrow Endothelial Progenitors on Functional and Cellular Components of Blood-Spinal Cord Barrier in ALS Mice

Abstract

Convincing evidence of blood-spinal cord barrier (BSCB) alterations has been demonstrated in amyotrophic lateral sclerosis (ALS) and barrier repair is imperative to prevent motor neuron dysfunction.We showed benefits of human bone marrow-derived CD34+ cells (hBM34+) and endothelial progenitor cells (hBM-EPCs) intravenous transplantation into symptomatic G93A SOD1 mutant mice on barrier reparative processes. These gains likely occurred by replacement of damaged endothelial cells, prolonging motor neuron survival. However, additional investigations are needed to confirm the effects of administered cells on integrity of the microvascular endothelium. The aim of this study was to determine tight junction protein levels, capillary pericyte coverage, microvascular basement membrane, and endothelial F-actin status in spinal cord capillaries of G93A SOD1 mutant mice treated with human bone marrow-derived stem cells. Tight junction proteins were detected in the spinal cords of cell-treated vs. nontreated mice via western blotting at four weeks post-transplant. Capillary pericyte, basement membrane laminin, and endothelial F-actin magnitudes were determined in cervical/lumbar spinal cord tissues in ALS mice, including controls, by immunohistochemistry and fluorescent staining. Results showed that celltreated vs. media-treated ALS mice substantially increased tight junction protein levels, capillary pericyte coverage, basement membrane laminin immunoexpressions, and endothelial cytoskeletal F-actin fluorescent expressions. The greatest benefits were detected in mice receiving hBM-EPCs vs. hBM34 + cells. These study results support treatment with a specific cell type derived from human bone marrow towards BSCB repair in ALS. Thus, hBM-EPCs may be advanced for clinical applications as a cellspecific approach for ALS therapy through restored barrier integrity.

Breached Barriers: A Scoping Review of Blood-Central Nervous System Barrier Pathology in Amyotrophic Lateral Sclerosis

“…Repair of the BCNSB pathology in ALS via stem cell transplantation has provided some evidence of symptomatic improvement in SOD1 G93A mice. The intravenous transplantation of human bone marrow-derived CD34+ cells (hBM34+) and endothelial progenitor cells (hBM-EPCs) enhanced the replacement of damaged endothelial cells in the CNS capillaries (Garbuzova-Davis et al, 2017 , 2018 , 2019 , 2021 ; Eve et al, 2018 ). One mechanism of hBM-EPCs on the endothelium includes excretion of extracellular vesicles that transfer biomolecules to facilitate the repair of damaged microvascular endothelium in ALS (Garbuzova-Davis et al, 2020 ).…”

“…One mechanism of hBM-EPCs on the endothelium includes excretion of extracellular vesicles that transfer biomolecules to facilitate the repair of damaged microvascular endothelium in ALS (Garbuzova-Davis et al, 2020 ). Additionally, mice receiving hBM-EPCs have increased tight junction protein levels, capillary pericyte coverage, and basement membrane laminin expression, all of which maintain capillary endothelium integrity (Garbuzova-Davis et al, 2021 ). Ultimately, these mechanisms may prevent the entry of immune or inflammatory mediators which can contribute to motor neuron dysfunction (Garbuzova-Davis et al, 2019 ).…”

Cellular and Noncellular Approaches for Repairing the Damaged Blood–CNS–Barrier in Amyotrophic Lateral Sclerosis

“…However, the impacts of cell transplantation on the integrity of the endothelium in murine CNS capillaries were not fully established. In a study by Garbuzova-Davis et al [ 53 ], functional and cellular constituents of the microvascular endothelium in the spinal cord were evaluated after the administration of hBM34 + cells and hBMEPCs, at the same dose of 1 × 10 6 cells, into G93A SOD1 mice. The findings showed that ALS mice receiving hBMEPC vs. hBM34 + cell treatment significantly increased the levels of TJ claudin-5, occludin, and ZO-1 proteins; enhanced the coverage of capillary pericytes; amended immunoexpression of basement membrane laminin; and increased expression of endothelial cytoskeletal F-actin.…”

Pericyte Loss in Diseases

“…Furthermore, a loss of pericytes in the choroid plexus has been detected in patients with ALS, coupled with a deregulation of the blood-cerebrospinal fluid (CSF) barrier [132]. In a murine model of ALS, reduced pericyte coverage in spinal cord capillaries has also been demonstrated [133]. Interestingly, the administration of adipose-derived pericytes has shown promising results in ALS mice, extending their survival and increasing antioxidant enzymes in the brain [134].…”