Reconstitution of degenerated ovine lumbar discs by STRO-3–positive allogeneic mesenchymal precursor cells combined with pentosan polysulfate

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>Disc degeneration and associated low-back pain are major causes of suffering and disability. The authors examined the potential of mesenchymal precursor cells (MPCs), when formulated with pentosan polysulfate (PPS), to ameliorate disc degeneration in an ovine model.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Twenty-four sheep had annular incisions made at L2–3, L3–4, and L4–5 to induce degeneration. Twelve weeks after injury, the nucleus pulposus of a degenerated disc in each animal was injected with ProFreeze and PPS formulated with either a low dose (0.1 million MPCs) or a high dose (0.5 million MPCs) of cells. The 2 adjacent injured discs in each spine were either injected with PPS and ProFreeze (PPS control) or not injected (nil-injected control). The adjacent noninjured L1–2 and L5–6 discs served as noninjured control discs. Disc height indices (DHIs) were obtained at baseline, before injection, and at planned death. After necropsy, 24 weeks after injection, the spines were subjected to MRI and morphological, histological, and biochemical analyses.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>Twelve weeks after the annular injury, all the injured discs exhibited a significant reduction in mean DHI (low-dose group 17.19%; high-dose group 18.01% [p &lt; 0.01]). Twenty-four weeks after injections, the discs injected with the low-dose MPC+PPS formulation recovered disc height, and their mean DHI was significantly greater than the DHI of PPS- and nil-injected discs (p &lt; 0.001). Although the mean Pfirrmann MRI disc degeneration score for the low-dose MPC+PPS–injected discs was lower than that for the nil- and PPS-injected discs, the differences were not significant. The disc morphology scores for the nil- and PPS-injected discs were significantly higher than the normal control disc scores (p &lt; 0.005), whereas the low-dose MPC+PPS–injected disc scores were not significantly different from those of the normal controls. The mean glycosaminoglycan content of the nuclei pulposus of the low-dose MPC+PPS–injected discs was significantly higher than that of the PPS-injected controls (p &lt; 0.05) but was not significantly different from the normal control disc glycosaminoglycan levels. Histopathology degeneration frequency scores for the low-dose MPC+PPS–injected discs were lower than those for the PPS- and Nil-injected discs. The corresponding high-dose MPC+PPS–injected discs failed to show significant improvements in any outcome measure relative to the controls.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>Intradiscal injections of a formulation composed of 0.1 million MPCs combined with PPS resulted in positive effects in reducing the progression of disc degeneration in an ovine model, as assessed by improvements in DHI and morphological, biochemical, and histopathological scores.</jats:p></jats:sec>

A Review of Animal Models of Intervertebral Disc Degeneration: Pathophysiology, Regeneration, and Translation to the Clinic

“…As described above injection of enzymes leads to proteoglycan loss, an essential component of the pathophysiological process of disc degeneration observed clinically. A criticism of the chondroitinase ABC for inducing disc degeneration is that the viability of native disc cells is largely preserved, enabling regeneration of the extracellular matrix [ 99 ].…”

Controversies in regenerative medicine: Should intervertebral disc degeneration be treated with mesenchymal stem cells?

“…While larger studies fulfilling these requirements are currently under way in various laboratories and results are eagerly awaited, it was previously already shown that MSCs are able to promote disc regeneration in dogs with experimentally induced IVD degeneration . Importantly, similar results were observed in sheep, not only after nucleotomy, but also after annular injury and annular incision, highlighting the therapeutic potential of MSCs in large animal models and hence possibly also in humans.…”

Ventral Surgical Approach for an Intervertebral Disc Degeneration and Regeneration Model in Sheep Cervical Spine: Anatomic Technical Description, Strengths and Limitations

“…11,17 Therefore, the ovine spine has been used as a model for intervertebral disc degeneration and test implant devices and in the preclinical investigation of cellular therapies. 7,11,[18][19][20] Analyses of sheep cervical spine biomechanics and radiological anatomy parameters confirmed a high similarity to measures in human cervical spines, which allow the use of similar sized implants and instruments as under clinical conditions in humans. 11,17 Compared with human cervical spine, the sheep disc is even higher in superior-inferior measures, which, according to the largely avascular nature of the intervertebral disc and dependence on diffusion to meet nutritional requirements, seems favourable for an ambitious disc regeneration model.…”

“…Ovine disc models have previously been described to analyse degeneration processes and preclinical regeneration therapies. 5,20 Most of these models use the sheep lumbar spine. Beside the fact that sheep are one of the most ideal disc models stated by Daly and colleagues until now, there is only limited data for disc degeneration and regeneration models in the ovine cervical spine.…”

“…11,17 Compared with human cervical spine, the sheep disc is even higher in superior-inferior measures, which, according to the largely avascular nature of the intervertebral disc and dependence on diffusion to meet nutritional requirements, seems favourable for an ambitious disc regeneration model. 11,20 The larger height of the intervertebral discs makes it also more feasible to apply a proper intervertebral disc-defect without damaging the endplates of the adjacent vertebrae, which is an advantage over the lumbar ovine discs which are thinner than the cervical intervertebral discs. 13 Nevertheless, from our experience, we recommend to use intraoperative radiographic c-arm imaging in both planes to confirm the right position of the defect and to guarantee no harm to the endplates of the adjacent vertebrae.…”