High density placental mesenchymal stromal cells provide neuronal preservation and improve motor function following in utero treatment of ovine myelomeningocele

Abstract

Purpose: The purpose of this study was to determine whether seeding density of placental mesenchymal stromal cells (PMSCs) on extracellular matrix (ECM) during in utero repair of myelomeningocele (MMC) affects motor function and neuronal preservation in the ovine model. Methods: MMC defects were surgically created in 33 fetuses and repaired following randomization into four treatment groups: ECM only (n=10), PMSC-ECM (42K cells/cm2) (n=8), PMSC-ECM (167K cells/cm2) (n=7), or PMSC-ECM (250–300K cells/cm2) (n=8). Motor function was evaluated using the Sheep Locomotor Rating Scale (SLR). Serial sections of the lumbar spinal cord were analyzed by measuring their cross-sectional area which were then normalized to normal lambs. Large neurons (LN, diameter 30–70μm) were counted manually and density calculated per mm2 gray matter. Results: Lambs treated with PMSCs at any density had a higher median SLR score (15 [IQR 13.5–15]) than ECM alone (6.5 [IQR 4–12.75], p=0.036). Cross-sectional areas of spinal cord and gray matter were highest in the PMSC-ECM (167K/cm2) group (p=0.002 and 0.006, respectively). LN density was highest in the greatest density PMSC-ECM (250–300K/cm2) group (p=0.045) which positively correlated with SLR score (r=0.807, p<0.0001). Conclusions: Fetal repair of myelomeningocele with high density PMSC-ECM resulted in increased large neuron density, which strongly correlated with improved motor function.

Spinal Angulation: A Limitation of the Fetal Lamb Model of Myelomeningocele

“…Treatment groups were defined as repair with ECM alone or ECM seeded with PMSCs at any density. The SLR scores for some of these lambs have been previously published (30/31); however, the effect of spinal angulation on functional outcomes has never been studied [17,18]. Spearman's rank-order correlation was used to analyze relationships between variables including SLR scores, level or degree of angulation, percentage of vertebral bone remaining, and normalized spinal cord height-to-width ratio.…”

“…The technique of MMC defect creation and repair described in this study differs from that originally described by Meuli et al [7] in the extent of the lumbar laminectomy and removal of the paraspinal muscles but has widely been adopted to prevent tissue regrowth over the defect and more accurately mimic human fetal repair [10,[18][19][20][21][22]. While scoring systems have been developed to characterize the surgically created defect, thereby increasing the rigor and reproducibility of the model, the effect of an in utero multisegment laminectomy on postnatal spinal morphology has not been previously described [10].…”

Hydrogel and neural progenitor cell delivery supports organotypic fetal spinal cord development in an ex vivo model of prenatal spina bifida repair

“…Due to their potential to engraft and to support endogenous neural cells within the host through immunomodulatory and trophic factors, the utility of mesenchymal stem cells has been more thoroughly investigated and has been beneficial in some MMC models of repair. 39,[48][49][50][51][52] The second major finding from our study is the successful establishment of an organotypic model specific to the affected lumbar spinal cord in fetal MMC. Specifically, slice cultures from MMC pups demonstrated robust survival of endogenous cells within fibrin hydrogels for up to 14 days and showed evidence of continued differentiation into mature neuronal phenotypes with robust neurite outgrowth along its periphery.…”

“…Due to their potential to engraft and to support endogenous neural cells within the host through immunomodulatory and trophic factors, the utility of mesenchymal stem cells has been more thoroughly investigated and has been beneficial in some MMC models of repair. 39 , 48 – 52 …”

Extracellular Matrix Mimicking Nanofibrous Scaffolds Modified With Mesenchymal Stem Cell-Derived Extracellular Vesicles for Improved Vascularization

“…Therefore, designing and constructing biomaterial scaffolds to mimic the structure of the EV-ECM complex and the physiological interactions between the ECM and EVs, represents an attractive and promising novel approach for tissue engineering applications. Mesenchymal stem cells (MSCs) isolated from various tissues are multipotent stem cells (Fridenshtein et al, 1968 ; Jo et al, 2007 ; Oh et al, 2008 ; Zannettino et al, 2008 ; Xue et al, 2018 ), represent a promising regenerative treatment for a variety of diseases (Bouffi et al, 2010 ; Lankford et al, 2015 , 2017 ; Wang et al, 2015 ; Brown et al, 2016 ; Hofer and Tuan, 2016 ; Kabagambe et al, 2017 ; Galganski et al, 2019 ; Vanover et al, 2019 ; Zhang Z. et al, 2019 ), especially vascular diseases (Pankajakshan and Agrawal, 2014 ; Premer et al, 2019 ), due to the biofunctional paracrine secretion, including EVs. However, in many of the cases where therapeutic effects were observed using MSCs, the transplanted stem cells did not persist following injection and thus did not contribute to tissue regeneration by integration.…”