The effects of human Wharton's jelly cell transplantation on the intervertebral disc in a canine disc degeneration model

Umbilical cord mesenchymal stem cells for regenerative treatment of intervertebral disc degeneration

Intervertebral disc degeneration is thought to be a major contributor to low back pain, the etiology of which is complex and not yet fully understood. To compensate for the lack of drug and surgical treatment, mesenchymal stem cells have been proposed for regenerative treatment of intervertebral discs in recent years, and encouraging results have been achieved in related trials. Mesenchymal stem cells can be derived from different parts of the body, among which mesenchymal stem cells isolated from the fetal umbilical cord have excellent performance in terms of difficulty of acquisition, differentiation potential, immunogenicity and ethical risk. This makes it possible for umbilical cord derived mesenchymal stem cells to replace the most widely used bone marrow-derived and adipose tissue derived mesenchymal stem cells as the first choice for regenerating intervertebral discs. However, the survival of umbilical cord mesenchymal stem cells within the intervertebral disc is a major factor affecting their regenerative capacity. In recent years biomaterial scaffolds in tissue engineering have aided the survival of umbilical cord mesenchymal stem cells by mimicking the natural extracellular matrix. This seems to provide a new idea for the application of umbilical cord mesenchymal stem cells. This article reviews the structure of the intervertebral disc, disc degeneration, and the strengths and weaknesses of common treatment methods. We focus on the cell source, cell characteristics, mechanism of action and related experiments to summarize the umbilical cord mesenchymal stem cells and explore the feasibility of tissue engineering technology of umbilical cord mesenchymal stem cells. Hoping to provide new ideas for the treatment of disc degeneration.

Allogenic Perinatal Tissue for Musculoskeletal Regenerative Medicine Applications: A Systematic Review

Producing tremendous amounts of stress and financial burden on the global patient population and healthcare systems around the world, most current modalities of treatment for musculoskeletal ailments often do not address the etiopathogenetic causes of these disorders. Regenerative medicine for musculoskeletal disorders relies on orthobiologics derived from either allogenic or autologous sources. Multiple drawbacks are associated with autologous sources, including donor-site morbidity, a dearth of studies, and variability in both patient reported and clinical/functional outcomes. On the other hand, allogenic sources address several of these concerns, and continue to be a suitable source of mesenchymal stem cells (MSCs). This review qualitatively reports both the preclinical and clinical outcomes of publications studying the applications of umbilical cord (-derived Wharton's jelly), amniotic suspension allograft, amniotic membrane, and amniotic fluid in musculoskeletal medicine. A systematic review was conducted utilizing the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines on studies published between January 2010 and October 2022 that used allogeneic perinatal tissues. Further randomized controlled clinical studies are necessary to properly evaluate the safety and efficacy of these tissues in orthopedic surgery.

Allogenic Umbilical Cord Tissue for Treatment of Knee Osteoarthritis

Interest in use of perinatal allogenic tissues including clinical-grade minimally manipulated umbilical cord tissue-derived allograft formulations to treat knee osteoarthritis (OA) patients is increasing. Limited studies have characterized these formulations and evaluated their safety and efficacy in knee OA patients. We developed such formulation and reported the presence of growth factors, cytokines, hyaluronic acid, and exosomes. We reported that its administration is safe, and resulted in 50% pain reduction and improvement in knee injury and osteoarthritis outcome score (over 10%) and 36-item short form survey (25%). Another study reported no adverse events post injection of similar formulation and statistically significant ( P <0.001) improvement in visual analog scale and Western Ontario and McMaster Universities Osteoarthritis Index scores and reduction in medication usage in patients (77.8%). We also summarized the clinical trials registered on ClinicalTrials.gov utilizing umbilical cord tissue for knee OA treatment. In conclusion, available studies are preliminary but pave the way to higher level appropriately powered investigations, and these formulations should be considered as nonoperative alternative to manage knee OA.

Umbilical cord mesenchymal stem cells promote the repair of trochlear groove reconstruction in dogs

Trochlear groove reconstruction (TGR) is a common treatment for patellar luxation (PL) in dogs. Nevertheless, the prognosis of TGR is poor due to the cartilage damage and secondary inflammation. To study the repair effect of canine umbilical cord mesenchymal stem cells (UC–MSCs) after TGR, 10 experimental dogs were given TGR surgery and then randomized into two groups: Treatment group (1 ml suspension allogeneic UC–MSCs (106 cells/kg) was injected into the cavum articulare on days 0, 7, and 14 after TGR); and the Model group (injected with 1 ml of physiological saline as negative control). The therapeutic effect of UC–MSCs was studied by blood routine examination, inflammatory factor index detection, double-blind knee score, histopathology, and computed tomography (CT) scans. The results showed that the total number of white blood cells and neutrophils in the model group were significantly higher than those in the treatment group on both 7 days and 21 days, postoperatively (P &lt; 0.05); there were no significant changes in the levels of IL-6, MMP-13, and TGF-β1 between the model group and the treatment group throughout the days of testing. The double-blind knee scores of the treatment group were significantly lower than the model group on 1st, 4th, and 5th days postoperatively (P &lt; 0.05). The treatment group showed low-pain sensation, stable gait, and fast recovery of muscle strength in the knee score, and the wound healing of the treatment group returned to normal on the 5th day after surgery; CT scans and gross observation showed that the cartilage growth in the treatment group was faster than that in the model group. Histological observation of cases showed that fibro chondrocytes were predominantly found in the treatment group, and the distribution of chondrocytes was uneven, while the model group showed a large number of fibrous tissue hyperplasia, fissures, and unequal matrix staining. Intra-articular injection of UC–MSCs after TGR has the effect of relieving pain and promoting the repair of bone defects, making the operative limb recover function earlier, making up for the deficiency of TGR, and improving the effect of PL treatment. Future studies should furthermore explore the dose and frequency of therapy based on the multiple advantages of UC–MSCs and the mechanism of cartilage repair in dogs.

Cell sources proposed for nucleus pulposus regeneration

Lower back pain (LBP) occurs in 80% of adults in their lifetime; resulting in LBP being one of the biggest causes of disability worldwide. Chronic LBP has been linked to the degeneration of the intervertebral disc (IVD). The current treatments for chronic back pain only provide alleviation of symptoms through pain relief, tissue removal, or spinal fusion; none of which target regenerating the degenerate IVD. As nucleus pulposus (NP) degeneration is thought to represent a key initiation site of IVD degeneration, cell therapy that specifically targets the restoration of the NP has been reviewed here. A literature search to quantitatively assess all cell types used in NP regeneration was undertaken. With key cell sources: NP cells; annulus fibrosus cells; notochordal cells; chondrocytes; bone marrow mesenchymal stromal cells; adipose-derived stromal cells; and induced pluripotent stem cells extensively analyzed for their regenerative potential of the NP. This review highlights: accessibility; expansion capability in vitro; cell survival in an IVD environment; regenerative potential; and safety for these key potential cell sources. In conclusion, while several potential cell sources have been proposed, iPSC may provide the most promising regenerative potential.

Umbilical Cord-Derived Wharton's Jelly for Regenerative Medicine Applications: A Systematic Review

Musculoskeletal ailments affect millions of people around the world and place a high burden on healthcare. Traditional treatment modalities are limited and do not address underlying pathologies. Mesenchymal stem cells (MSCs) have emerged as an exciting therapeutic alternative and Wharton’s jelly-derived mesenchymal stem cells (WJSCs) are some of these. This review reports the clinical and functional outcomes of the applications of WJSCs in orthopedic surgery. A systematic review was conducted utilizing the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The studies that used culture-expanded, mesenchymal stem or stromal cells, MSCs and/or connective tissues procured from Wharton’s jelly (WJ), from January 2010 to October 2021, were included. Conventional non-operative therapies and placebos were used as comparisons. Six studies that directly discussed WJSCs use in an animal model or the basic scientific testing using an injury model were identified. Five publications studied cartilage injury, three studied degenerative disc disease, one was related to osteoarthritis, and one was related to osteochondral defects. The results of these studies suggested the benefits of WJSCs in the management of these orthopedic pathologies. To adequately assess the safety and efficacy of WJSCs in orthopedic surgery, further randomized controlled clinical studies are necessary.

Human umbilical cord-derived mesenchymal stem cells and their chondroprogenitor derivatives reduced pain and inflammation signaling and promote regeneration in a rat intervertebral disc degeneration model

Intervertebral disc (IVD) degeneration is an asymptomatic pathophysiological condition and a strong causative factor of low back pain. There is no cure available except spinal fusion and pain management. Stem cell-based regenerative medicine is being considered as an alternative approach to treat disc diseases. The current study aimed to differentiate human umbilical cord-mesenchymal stem cells (hUC-MSCs) into chondrocyte-like cells and to elucidate their feasibility and efficacy in the degenerated IVD rat model. Chondrogenic induction medium was used to differentiate hUC-MSCs into chondroprogenitors. Rat tail IVD model was established with three consecutive coccygeal discs. qPCR was performed to quantify the molecular markers of pain and inflammation. Histological staining was performed to evaluate the degree of regeneration. Induced chondroprogenitors showed the expression of chondrogenic genes, SOX9, TGF-β1, ACAN, BMP2, and GDF5. Immunocytochemical staining showed positive expression of chondrogenic proteins SOX9, TGF-β1, TGF-β2, and Collagen 2. In in vivo study, transplanted chondroprogenitors showed better survival, homing, and distribution in IVD as compared to normal MSCs. Expression of pain and inflammatory genes at day 5 of cell transplantation modulated immune response significantly. The transplanted labeled MSCs and induced chondroprogenitors differentiated into functional nucleus pulposus (NP) cells as evident from co-localization of red (DiI) and green fluorescence for SOX9, TGF-β1, and TGF-β2. Alcian blue and H & E staining showed standard histological features, indicating better preservation of the NP structure and cellularity than degenerated discs. hUC-MSCs-derived chondroprogenitors showed better regeneration potential as compared to normal MSCs. The pain and inflammation genes were downregulated in the treated group as compared to the degenerated IVD.

Directed Differentiation of Notochord-like and Nucleus Pulposus-like Cells Using Human Pluripotent Stem Cells

Intervertebral disc degeneration might be amenable to stem cell therapy, but the required cells are scarce. Here, we report the development of a protocol for directed in vitro differentiation of human pluripotent stem cells (hPSCs) into notochord-like and nucleus pulposus (NP)-like cells of the disc. The first step combines enhancement of ACTIVIN/NODAL and WNT and inhibition of BMP pathways. By day 5 of differentiation, hPSC-derived cells express notochordal cell characteristic genes. After activating the TGF-β pathway for an additional 15 days, qPCR, immunostaining, and transcriptome data show that a wide array of NP markers are expressed. Transcriptomically, the in vitro-derived cells become more like in vivo adolescent human NP cells, driven by a set of influential genes enriched with motifs bound by BRACHYURY and FOXA2, consistent with an NP cell-like identity. Transplantation of these NP-like cells attenuates fibrotic changes in a rat disc injury model of disc degeneration.

Comprehensive RNA expression profile of therapeutic adipose‑derived mesenchymal stem cells co‑cultured with degenerative nucleus pulposus cells

Stem cell-based therapy is a promising alternative to conventional approaches to treating intervertebral disc degeneration (IDD). However, comprehensive understanding of stem cell-based therapy at the gene level is still lacking. In the present study, we identified the expression profiles of messenger RNAs (mRNAs) and long non-coding RNAs (lncRNAs) expressed within a co-culture system of adipose-derived mesenchymal stem cells (ASCs) and degenerative nucleus pulposus cells (NPCs) and explored the signaling pathways involved and their regulatory networks. Microarray analysis was used to compare ASCs co-cultured with degenerative NPCs to ASCs cultured alone, and the underlying regulatory pattern, including the signaling pathways and competing endogenous RNA (ceRNA) network, was analyzed with robust bioinformatics methods. The results showed that 360 lncRNAs and 1757 mRNAs were differentially expressed by ASCs, and the microarray results were confirmed by quantitative PCR. Moreover, 589 Gene Ontology terms were upregulated, whereas 661 terms were downregulated. A total of 299 signaling pathways were significantly altered. A Path-net and a Signal-net were built to show interactions among differentially expressed genes. An mRNA-lncRNA co-expression network was constructed to reveal the interplay among differentially expressed mRNAs and lncRNAs, whereas a ceRNA network was built to investigate their connections with microRNAs involved in IDD. To the best of our knowledge, this original and comprehensive exploration reveals differentially expressed lncRNAs and mRNAs of ASCs stimulated by degenerative NPCs, underscoring the regulation pattern within the co-culture system at the gene level. These data may further understanding of NPC-directed differentiation of ASCs and facilitate the application of ASCs in future treatments for IDD.

Animal models of regenerative medicine for biological treatment approaches of degenerative disc diseases

Degenerative disc disease (DDD) is a painful, chronic and progressive disease, which is characterized by inflammation, structural and biological deterioration of the intervertebral disc (IVD) tissues. DDD is specified as cell-, age-, and genetic-dependent degenerative process that can be accelerated by environmental factors. It is one of the major causes of chronic back pain and disability affecting millions of people globally. Current treatment options, such as physical rehabilitation, pain management, and surgical intervention, can provide only temporary pain relief. Different animal models have been used to study the process of IVD degeneration and develop therapeutic options that may restore the structure and function of degenerative discs. Several research works have depicted considerable progress in understanding the biological basis of disc degeneration and the therapeutic potentials of cell transplantation, gene therapy, applications of supporting biomaterials and bioactive factors, or a combination thereof. Since animal models play increasingly significant roles in treatment approaches of DDD, we conducted an electronic database search on Medline through June 2020 to identify, compare, and discuss publications regarding biological therapeutic approaches of DDD that based on intradiscal treatment strategies. We provide an up-to-date overview of biological treatment strategies in animal models including mouse, rat, rabbit, porcine, bovine, ovine, caprine, canine, and primate models. Although no animal model could profoundly reproduce the clinical conditions in humans; animal models have played important roles in specifying our knowledge about the pathophysiology of DDD. They are crucial for developing new therapy approaches for clinical applications.

Advances in translational orthopaedic research with species-specific multipotent mesenchymal stromal cells derived from the umbilical cord

Compliance with current regulations for the development of innovative medicines require the testing of candidate therapies in relevant translational animal models prior to human use. This poses a great challenge when the drug is composed of cells, not only because of the living nature of the active ingredient but also due to its human origin, which can subsequently lead to a xenogeneic response in the animals. Although immunosuppression is a plausible solution, this is not suitable for large animals and may also influence the results of the study by altering mechanisms of action that are, in fact, poorly understood. For this reason, a number of procedures have been developed to isolate homologous species-specific cell types to address preclinical pharmacodynamics, pharmacokinetics and toxicology. In this work, we present and discuss advances in the methodologies for derivation of multipotent Mesenchymal Stromal Cells derived from the umbilical cord, in general, and Wharton's jelly, in particular, from medium to large animals of interest in orthopaedics research, as well as current and potential applications in studies addressing proof of concept and preclinical regulatory aspects.

Potential of Human Nucleus Pulposus-Like Cells Derived From Umbilical Cord to Treat Degenerative Disc Disease

BACKGROUND

Degenerative disc disease (DDD) is a common spinal disorder that manifests with neck and lower back pain caused by the degeneration of intervertebral discs (IVDs). Currently, there is no treatment to cure this debilitating ailment.

OBJECTIVE

To investigate the potential of nucleus pulposus (NP)-like cells (NPCs) derived from human umbilical cord mesenchymal stem cells (MSCs) to restore degenerated IVDs using a rabbit DDD model.

METHODS

NPCs differentiated from MSCs were characterized using quantitative real-time reverse transcription polymerase chain reaction and immunocytochemical analysis. MSCs and NPCs were labeled with fluorescent dye, PKH26, and transplanted into degenerated IVDs of a rabbit model of DDD (n = 9 each). Magnetic resonance imaging of the IVDs was performed before and after IVD degeneration, and following cell transplantation. IVDs were extracted 8 wk post-transplantation and analyzed by various biochemical, immunohistological, and molecular techniques.

RESULTS

NPC derivatives of MSCs expressed known NP-specific genes, SOX9, ACAN, COL2, FOXF1, and KRT19. Transplanted cells survived, dispersed, and integrated into the degenerated IVDs. IVDs augmented with NPCs showed significant improvement in the histology, cellularity, sulfated glycosaminoglycan and water contents of the NP. In addition, expression of human genes, SOX9, ACAN, COL2, FOXF1, KRT19, PAX6, CA12, and COMP, as well as proteins, SOX9, ACAN, COL2, and FOXF1, suggest NP biosynthesis due to transplantation of NPCs. Based on these results, a molecular mechanism for NP regeneration was proposed.

CONCLUSION

The findings of this study demonstrating feasibility and efficacy of NPCs to regenerate NP should spur interest for clinical studies to treat DDD using cell therapy.

Degenerative cervical myelopathy: Recent updates and future directions

Advances in patient selection, surgical techniques, and postoperative care have facilitated spine surgeons to manage complex spine cases with shorter operative times, reduced hospital stay and improved outcomes. We focus this article on a few areas which have shown maximum developments in management of degenerative cervical myelopathy and also throw a glimpse into the future ahead. Imaging modalities, surgical decision making, robotics and neuro-navigation, minimally invasive spinal surgery, motion preservation, use of biologics are few of them. Through this review article, we hope to provide the readers with an insight into the present state of art in cervical myelopathy and what the future has in store for us.

Intervertebral disc regeneration: From cell therapy to the development of novel bioinspired endogenous repair strategies

Low back pain (LBP), frequently associated with intervertebral disc (IVD) degeneration, is a major public health concern. LBP is currently managed by pharmacological treatments and, if unsuccessful, by invasive surgical procedures, which do not counteract the degenerative process. Considering that IVD cell depletion is critical in the degenerative process, the supplementation of IVD with reparative cells, associated or not with biomaterials, has been contemplated. Recently, the discovery of reparative stem/progenitor cells in the IVD has led to increased interest in the potential of endogenous repair strategies. Recruitment of these cells by specific signals might constitute an alternative strategy to cell transplantation. Here, we review the status of cell-based therapies for treating IVD degeneration and emphasize the current concept of endogenous repair as well as future perspectives. This review also highlights the challenges of the mobilization/differentiation of reparative progenitor cells through the delivery of biologics factors to stimulate IVD regeneration.

Therapeutic effects of cell therapy with neonatal human dermal fibroblasts and rabbit dermal fibroblasts on disc degeneration and inflammation

BACKGROUND CONTEXT

Increasing evidence suggests transplanting viable cells into the degenerating intervertebral disc (IVD) may be effective in treating disc degeneration and back pain. Clinical studies utilizing autologous or allogeneic mesenchymal stem cells to treat patients with back pain have reported some encouraging results. Animal studies have shown that cells injected into the disc can survive for months and have regenerative effects. Studies to determine the advantages and disadvantages of cell types and sources for therapy are needed.

PURPOSE

The objective of this study is to determine the impact of donor source on the therapeutic effects of dermal fibroblast treatment on disc degeneration and inflammation.

STUDY DESIGN

Using the rabbit disc degeneration model, we compared transplantation of neonatal human dermal fibroblasts (nHDFs) and rabbit dermal fibroblasts (RDFs) into rabbit degenerated discs on host immune response, disc height, and IVD composition.

METHODS

New Zealand white rabbits received an annular puncture using an 18-guage needle to induce disc degeneration. Four weeks after injury, rabbit IVDs were treated with 5 × 10⁶ nHDFs, RDFs, or saline. At eight weeks post-treatment, animals were sacrificed. X-ray images were obtained. IVDs were isolated for inflammatory and collagen gene expression analysis using real-time polymerase chain reaction and biochemical analysis of proteoglycan contents using dimethylmethylene blue assay. These studies were funded by a research grant from SpinalCyte, LLC ($414,431).

RESULTS

Eight weeks after treatment, disc height indexes of discs treated with nHDF increased significantly by 7.8% (p<.01), whereas those treated with saline or RDF increased by 1.5% and 2.0%, respectively. Gene expression analysis showed that discs transplanted with nHDFs and RDFs displayed similar inflammatory responses (p=.2 to .8). Compared to intact discs, expression of both collagen types I and II increased significantly in nHDF-treated discs (p<.05), trending to significant in RDF-treated discs, and not significantly in saline treated discs. The ratio of collagen type II/collagen type I was higher in the IVDs treated with nHDFs (1.26) than those treated with RDFs (0.81) or saline (0.59) and intact discs (1.00). Last, proteoglycan contents increased significantly in discs treated with nHDF (p<.05) and were trending toward significance in the RDF-treated discs compared to those treated with saline.

CONCLUSIONS

This study showed that cell transplantation with nHDF into degenerated IVDs can significantly increase markers of disc regeneration (disc height, collagen type I and II gene expression, and proteoglycan contents). Transplantation with RDFs showed similar regenerative trends, but these trends were not significant. This study also showed that the human cells transplanted into the rabbit discs did not induce a higher immune response than the rabbit cells. These results support that the IVD is immune privileged and would tolerate allogeneic or xenogeneic grafts.

Aberrantly expressed messenger RNAs and long noncoding RNAs in degenerative nucleus pulposus cells co-cultured with adipose-derived mesenchymal stem cells

Background

Stem cell therapy is considered as a promising alternative to treat intervertebral disc degeneration (IDD). Extensive work had been done on identifying and comparing different types of candidate stem cells, both in vivo and in vitro. However, few studies have shed light on degenerative nucleus pulposus cells (NPCs), especially their biological behavior under the influence of exogenous stem cells, specifically the gene expression and regulation pattern. In the present study, we aimed to determine messenger RNAs (mRNAs) and long non-coding RNAs (lncRNAs), which are differentially expressed during the co-culturing process with adipose-derived mesenchymal stem cells (ASCs) and to explore the involved signaling pathways and the regulatory networks.

Methods

We compared degenerative NPCs co-cultured with ASCs with those cultured solely using lncRNA-mRNA microarray analysis. Based on these data, we investigated the significantly regulated signaling pathways based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database. Moreover, 23 micro RNAs (miRNAs), which were demonstrated to be involved in IDD were chosen; we investigated their theoretic regulatory importance associated with our microarray data.

Results

We found 632 lncRNAs and 1682 mRNAs were differentially expressed out of a total of 40,716 probes. We then confirmed the microarray data by real-time PCR. Furthermore, we demonstrated 197 upregulated, and 373 downregulated Gene Ontology terms and 176 significantly enriched pathways, such as the mitogen-activated protein kinase (MAPK) pathway. Also, a signal-net was constructed to reveal the interplay among differentially expressed genes. Meanwhile, a mRNA-lncRNA co-expression network was constructed for the significantly changed mRNAs and lncRNAs. Also, the competing endogenous RNA (ceRNA) network was built.

Conclusion

Our results present the first comprehensive identification of differentially expressed lncRNAs and mRNAs of degenerative NPCs, altered by co-culturing with ASCs, and outline the gene expression regulation pattern. These may provide valuable information for better understanding of stem cell therapy and potential candidate biomarkers for IDD treatment.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1677-x) contains supplementary material, which is available to authorized users.

The chondrodystrophic dog: A clinically relevant intermediate-sized animal model for the study of intervertebral disc-associated spinal pain

Low back pain (LBP) is the leading cause of disability worldwide, with an estimated 80% of the American population suffering from a painful back condition at some point during their lives. The most common cause of LBP is intervertebral disc (IVD) degeneration (IVDD), a condition that can be difficult to treat, either surgically or medically, with current available therapies. Thus, understanding the pathological mechanisms of IVDD and developing novel treatments are critical for improving outcome and quality of life in people living with LBP. While experimental animal models provide valuable mechanistic insight, each model has limitations that complicate translation to the clinical setting. This review focuses on the chondrodystrophic canine clinical model of IVDD as a promising model to assess IVD‐associated spinal pain and translational therapeutic strategies for LBP. The canine IVD, while smaller in size than human, goat, ovine, and bovine IVDs, is larger than most other small animal IVDD models and undergoes maturational changes similar to those of the human IVD. Furthermore, both dogs and humans develop painful IVDD as a spontaneous process, resulting in similar characteristic pathologies and clinical signs. Future exploration of the canine model as a model of IVD‐associated spinal pain and biological treatments using the canine clinical model will further demonstrate its translational capabilities with the added ethical benefit of treating an existing veterinary patient population with IVDD.

Quantitative magnetic resonance imaging for diagnosis of intervertebral disc degeneration of the cervico-thoracic junction: a pilot study

This study aimed to appraise two quantitative magnetic resonance imaging techniques, T2* imaging and diffusion-weighted imaging (DWI), for the diagnosis of the intervertebral disc degeneration of the cervico-thoracic junction. Influence of specific factors and diagnostic accuracy of both techniques were particularly explored. Sixty-one volunteers with neck and upper back pain were recruited and evaluated with both T2* imaging and DWI. The Pfirrmann grade, T2* relaxation time and apparent diffusion coefficient (ADC) value of each disc between C7 and T3 were recorded. Stratified analyses were performed for different anatomic levels, genders, age ranges and Pfirrmann grades. The diagnostic accuracy of both techniques was investigated using the receiver operating characteristic (ROC) curves. No statistically significant difference of either T2* relaxation time or ADC value was detected between males and females. Both parameters decreased with the increasing age and Pfirrmann grade. The ROC curves showed the higher sensitivity and specificity for T2* imaging than DWI to quantitatively identify the disc degeneration. Particularly, T2* imaging allowed for a quantitative distinguishing the normal, mild and moderate disc degeneration from the severe degeneration, which was unable to accomplish with DWI. In conclusion, we demonstrated that T2* imaging possess a better accuracy than DWI to quantitatively diagnose the intervertebral disc degeneration at the cervico-thoracic junction.

Human Wharton's Jelly Cells Activate Degenerative Nucleus Pulposus Cells In Vitro

To investigate the interaction between human Wharton's jelly cells (WJCs) and degenerative nucleus pulposus cells (NPCs), human WJCs were cocultured with degenerative NPCs with or without direct cell-cell contact. WJCs were isolated from the human umbilical cord and degenerative NPCs were isolated from the surgically obtained degenerative intervertebral disc tissue. The isolated WJCs positively expressed CD73, CD105, CD90, CD29, CD166, and human leukocyte antigen (HLA)-ABC, but negatively expressed CD34, CD45, and HLA-DR. After coculturing with three different WJCs:NPCs ratios for 7 days, the real-time polymerase chain reaction showed that the relative gene expression of nucleus pulposus (NP)-marker genes [aggrecan, type II collagen, and SRY-type HMG box-9 (SOX-9)] was significantly upgraded in all coculture groups (all p < 0.05 compared with control groups). Coculture either with or without cell-cell contact significantly activated the expression of NP-maker genes than controls, but coculture with cell-cell contact yielded a higher gene expression than coculture without cell-cell contact. In coculturing with cell-cell contact and WJCs:NPCs of 25:75, the relative gene expression of aggrecan, type II collagen, SOX-9 for WJCs yielded the highest increase by 721-, 1507-, and 1463-folds, respectively (all p < 0.05 compared with WJCs control). In contrast, the highest relative gene expression of aggrecan, type II collagen, SOX-9 for NPCs was 112-, 84-, and 109-folds, respectively, in coculture with cell-cell contact and in WJCs:NPCs of 75:25 (all p < 0.05 compared with NPCs control). In conclusion, the data indicated that coculturing human WJCs with degenerative NPCs induced the NP-like cell differentiation of WJCs and restored the biological status of degenerative NPCs and coculture WJCs and NPCs with direct cell-cell contact yielded more favorable gene expressions.

Characteristics and potentials of stem cells derived from human degenerated nucleus pulposus: potential for regeneration of the intervertebral disc

BACKGROUND

Eliminating the symptoms during treatment of intervertebral disc degeneration (IVDD) is only a temporary solution that does not cure the underlying cause. A biological method to treat this disorder may be possible by the newly discovered nucleus pulposus derived stem cells (NPDCs). However, the uncertain characteristics and potential of NPDCs calls for a comprehensive study.

METHODS

In the present study, nucleus pulposus samples were obtained from 5 patients with IVDD undergoing discectomy procedure and NPDCs were harvested using fluorescence activated cell sorting (FACS) by the co-expression of GD2+ and Tie2+. After in vitro expansion, the properties of NPDCs were compared with those of bone marrow mesenchyme stem cells (BMSCs) from the same subjects.

RESULTS

NPDCs performed similar properties in cell colony-forming ability, cell proliferation rate, cell cycle and stem cell gene expression similar to those of BMSCs. In addition, NPDCs could be differentiated into osteoblasts, adipocytes, and chondrocytes, and are found to be superior in chondrogenesis but inferior in adipocyte differentiation.

CONCLUSIONS

NPDCs derived from the degenerated intervertebral disc still keep the regeneration ability similar to BMSCs. Besides, the superior capacity in chondrogenesis may provide a promising cell candidate for cell-based regenerative medicine and tissue engineering in IVDD.

* Coculture with Partial Digestion Notochordal Cell-Rich Nucleus Pulposus Tissue Activates Degenerative Human Nucleus Pulposus Cells

Recent studies suggested that notochordal cells (NCs) and NC-conditioned medium (NCCM) can stimulate cell viability and matrix production of nucleus pulposus cells (NPCs). However, the potential of notochordal cell-rich nucleus pulposus (NRNP) incorporating the native environment of the intervertebral disc (IVD) has not been evaluated. The objective of this study was to develop an optimal NRNP model and test whether it can allow a significant level of NPC activation in vitro. Rabbit NRNP explants were divided into three groups according to different digestion time: digestion NRNP of 8 h, partial digestion NRNP of 2 h, and natural NRNP. Cell viability and NC phenotype were compared between these groups after 14 days of incubation. The products of the selected partial digestion NRNP group were then cocultured with human degenerated NPCs for 14 days. NPC viability, cell proliferation and senescence, the production of glycosaminoglycan (GAG) found in extracellular matrix, and NP matrix production by NPCs were assessed. The results showed that coculturing with partial digestion NRNP significantly improved the cell proliferation, cell senescence, and disc matrix gene expression of NPCs compared with those in the monoculture group. In addition, GAG/DNA ratio in the coculture group increased significantly, while the level of collagen II protein remained unchanged. In this study, we demonstrated that partial digestion NRNP may show a promising potential for NPC regeneration in IVD tissue engineering.

BMP7-Based Functionalized Self-Assembling Peptides Protect Nucleus Pulposus-Derived Stem Cells From Apoptosis In Vitro

Tissue engineering has shown great success in the treatment of intervertebral disk degeneration (IVDD) in the past decade. However, the adverse and harsh microenvironment associated in the intervertebral disks remains a great obstacle for the survival of transplanted cells. Although increasing numbers of new materials have been created or modified to overcome this hurdle, a new effective strategy of biological therapy is still required. In this study, bone morphogenic protein 7 (BMP7)-based functionalized self-assembling peptides were developed by conjugating a bioactive motif from BMP-7 (RKPS) onto the C-terminal of the peptide RADARADARADARADA (RADA16-I) at a ratio of 1:1 to form a new RADARKPS peptide. Human nucleus pulposus-derived stem cells (NPDCs) were cultured in the presence of RADA-RKPS or RADA16-I in an apoptosis-promoting environment that was induced by tumor necrosis factor-alpha, and cells were cultured with RADA16-I in normal medium that served as the control group. After 48 h of apoptosis induction, the viability, proliferation, apoptosis rate, and expression of apoptosis-related genes of NPDCs in the different groups were evaluated, and the differentiation of NPDCs toward nucleus pulposus-like cells was tested. The results showed that the RADA-RKPS peptide could significantly protect the survival and proliferation of NPDCs. In addition, the application of RADA-RKPS decreased the rate of cell apoptosis, as detected by TUNEL-positive staining. Furthermore, our in vitro study confirmed the apoptosis-protecting effects of RADA-RKPS peptides, which significantly reduced the BAX/BCL-2 ratio of NPDCs and upregulated the gene expression of collagen II a1, aggrecan, and Sox-9 after 48 h of apoptosis induction. Collectively, these lines of evidence suggest that RADA-RKPS peptides confer a protective effect to NPDCs in an apoptosis environment, suggesting their potential application in the development of new biological treatment strategies for IVDD.