Efficacy of administered mesenchymal stem cells in the initiation and co‐ordination of repair processes by resident disc cells in an ovine (Ovis aries) large destabilizing lesion model of experimental disc degeneration

Abstract

Background Forty percent of low back pain cases are due to intervertebral disc degeneration (IVDD), with mesenchymal stem cells (MSCs) a reported treatment. We utilized an ovine IVDD model and intradiscal heterologous MSCs to determine therapeutic efficacy at different stages of IVDD. Methodology Three nonoperated control (NOC) sheep were used for MSC isolation. In 36 sheep, 6 × 20 mm annular lesions were made at three spinal levels using customized blades/scalpel handles, and IVDD was allowed to develop for 4 weeks in the Early (EA) and late Acute (LA) groups, or 12 weeks in the chronic (EST) group. Lesion IVDs received injections of 10 × 10 6 MSCs or PBS, and after 8 (EA), 22 (LA) or 14 (EST) weeks recuperation the sheep were sacrificed. Longitudinal lateral radiographs were used to determine disc heights. IVD glycosaminoglycan (GAG) and hydroxyproline contents were quantified using established methods. An Instron materials testing machine and customized jigs analyzed IVD (range of motion, neutral zone [NZ] and stiffness) in flexion/extension, lateral bending and axial rotation. qRTPCR gene profiles of key anabolic and catabolic matrix molecules were undertaken. Toluidine blue and hematoxylin and eosin stained IVD sections were histopathologically scoring by two blinded observers. Results IVDD significantly reduced disc heights. MSC treatment restored 95% to 100% of disc height, maximally improved NZ and stiffness in flexion/extension and lateral bending in the EST group, restoring GAG levels. With IVDD qRTPCR demonstrated elevated catabolic gene expression ( MMP2/3/9/13, ADAMTS4/5 ) in the PBS IVDs and expession normalization in MSC‐treated IVDs. Histopathology degeneracy scores were close to levels of NOC IVDs in MSC IVDs but IVDD developed in PBS injected IVDs. Discussion Administered MSCs produced recovery in degenerate IVDs, restored disc height, composition, biomechanical properties, down regulated MMPs and fibrosis, strongly supporting the efficacy of MSCs for disc repair.

Spatiotemporal Expression of 3-B-3(−) and 7-D-4 Chondroitin Sulfation, Tissue Remodeling, and Attempted Repair in an Ovine Model of Intervertebral Disc Degeneration

“…20 After conducting numerous studies with the ovine model either in its original format using a 5-mm deep annular lesion 23 or in the modified form using a 6 × 20mm lesion 51 it became apparent that a number of IVD regenerative features were also apparent. 21,22 Spontaneous repair of the outermost annular layers was a consistent feature with type I collagen spanning the original annular surgical incision. 84 This material had a disorganized , which is also shown diagrammatically (d).…”

“…18,19 The ovine model was developed to evaluate aspects of IVDD but was also useful in studies on disc regeneration and prospective treatments to either slow or prevent DDD or stimulate IVD regeneration. [20][21][22] The ovine model of 1990 23,24 used a controlled 5-mm deep annular lesion, which produced IVDD over an 18-month period and was characterized using biochemical, 25 histochemical, Western blotting of aggrecan catabolism, 26,27 and biomechanical evaluation. [28][29][30][31][32] A steady decline in IVD proteoglycan/catabolism of aggrecan were major features, 26,33 upregulation in decorin and biglycan biosynthesis, fragmentation of fibromodulin and biglycan was also observed 27,34 with roles in collagen fibrillogenesis, matrix assembly, and signal transduction important in IVD regeneration.…”

“…31,49,50 A modification of this model was developed in 2012 using a 6 × 20 mm annular lesion, 51 biochemical, compositional, gene profiling, and histopathological scoring confirmed its degenerative features. 22 Exogenously administered mesenchymal stem cells (MSCs) promoted repair of the annular lesion. Hyaluronan (HA) oligosaccharides generated by depolymerization of HA during IVDD promoted extracellular matrix (ECM) remodeling through matrix metalloproteinases (MMPs) and spontaneous repair of the outer annular defect.…”

Intervertebral Disc Degeneration Is Associated With Aberrant Endplate Remodeling and Reduced Small Molecule Transport

“…For instance, numerous studies have considered the injection of progenitor cell populations into NP, either alone or within a hydrogel carrier, to improve function . Although this has shown some efficacy in animal models, animal discs are a fraction of the size of human lumbar discs and are therefore less nutritionally challenged. In humans, a reduction in diffusion into the disc is likely to adversely impact the viability and metabolic activity of delivered cells, thus reducing their regenerative potential.…”

Wnt3a and wnt5a as Potential Chondrogenic Stimulators for Nucleus Pulposus Cell Induction: A Comprehensive Review

“…Moreover, it remains undetermined whether the primary effect of transplanted cells is their immunomodulatory effects, endemic cell reactivation, active contribution to matrix production, or a combination thereof. [91][92][93] Nonetheless, MSCs are being explored in clinical setting, and their primary data suggest MSC transplantation to be safe and able to provoke clinical improvements. 7 In order to enhance the potency of MSCs to succeed in the IVD, multiple studies have explored the potential of preconditioning cells prior to IVD transplantation.…”