The fate of transplanted xenogeneic bone marrow‐derived stem cells in rat intervertebral discs

Abstract

Intervertebral disc degeneration is a major cause and a risk factor for chronic low back pain. The potential of using stem cells to treat disc degeneration has been raised. The aims of our study were to assess whether xenogeneic bone-marrow derived stem cells could survive in a rat disc degeneration model and to determine which cell types, if any, survived and differentiated into disc-like cells. Human bone-marrow derived CD34 þ (hematopoietic progenitor cells) and CD34 À (nonhematopoietic progenitor cells, including mesenchymal stem cells) cells were isolated, fluorescent-labeled, and injected into rat coccygeal discs. The rats were sacrificed at day 1, 10, 21, and 42. Treated discs were examined by histological and immunostaining techniques and compared to control discs. The survival of transplanted cells was further confirmed with a human nuclear specific marker. Fluorescent labeled CD34 À cells were detected until day 42 in the nucleus pulposus of the injected discs. After 3 weeks these cells had differentiated into cells expressing chondrocytic phenotype . In contrast, the fluorescent labeled CD34 þ cells could not be detected after day 21. No fluorescence-positive cells were detected in the noninjected control discs. Further, no inflammatory cells infiltrated the nucleus pulposus, even though these animals had not received immunosuppressive treatment. Our data provide evidence that transplanted human BM CD34 À cells survived and differentiated within the relative immune privileged nucleus pulposus of intervertebral disc degeneration. ß

Methods to monitor distribution and metabolic activity of mesenchymal stem cells following in vivo injection into nucleotomized porcine intervertebral discs

“…Mean ± SD is shown. *P \ 0.05 versus day 0; **P \ 0.005 versus day 0 corroborates studies of others who found transplanted human MSCs to be detectable at 42 days in a xenogenic rat model [55] or in a xenogenic minipig model even after 6 months [27]. Sakai et al used gene transfer of green fluorescent protein (GFP) for cell detection, and thus a convincing cell labeling technique found, that GFP-positive MSCs were detected in the nucleus from 2 to 48 weeks post-transplantation; these cells increased proportionally over time, suggesting that some of the cells had survived and proliferated [48].…”

“…Although xenogenic studies showed that human mRNA signals and co-localization of matrix proteins with implanted cells were retained at 6 weeks [55] or 6 months [27] after implantation, neither study addressed the question of implantation efficiency, implant retainment, or quantity of remaining anabolic active cells. Thus, we can only speculate, how much of the initially transferred cells contributed to the reported results.…”

“…In a xenogenic rat coccygeal disc model, Wei et al [55] reported no significant initial reduction in the amount of celltracker-orange (CTO?) labeled human CD34-cells over 42 days in vivo.…”

Mesenchymal progenitor cells combined with pentosan polysulfate mediating disc regeneration at the time of microdiscectomy: a preliminary study in an ovine model

“…1,2,10,16,20,22,25,[30][31][32][34][35][36][37][38]46,48,49,53,54,56,57,60,62,[64][65][66][67]69,73,83,90 The EuroDISC study, by Meisel and colleagues, 49 investigated the percutaneous transplantation of autologous disc chondrocytes. Following microdiscectomy, disc chondrocytes were harvested and expanded in vitro and were subsequently injected into the NP 3 months postoperatively.…”

“…Multiple preclinical animal studies have demonstrated the efficacy of intradiscally injected mesenchymal stem cells (MSCs) to induce disc regeneration. 1,2,16,18,20,21,25,[31][32][33][34]38,39,49,53,56,60,[64][65][66]69,73,83,87,90 Allogeneic mesenchymal progenitor cells (MPCs) are the earliest uncommitted clonogenic population of bone marrow stromal cells and have also successfully repaired the extracellular matrix following their injection into degenerative ovine discs. 25 Moreover, when ovine MPCs combined with the chondrogenic agent pentosan polysulfate (PPS) were embedded in a gelatin sponge and placed in a biodegradable cage that was implanted into the interbody space of ovine cervical spines, the cage became filled with a predominately cartilaginous matrix.…”