Evaluation of platelet-rich plasma and hydrostatic pressure regarding cell differentiation in nucleus pulposus tissue engineering

Orthobiologic Management Options for Degenerative Disc Disease

Degenerative disc disease (DDD) is a pervasive condition that limits quality of life and burdens economies worldwide. Conventional pharmacological treatments primarily aimed at slowing the progression of degeneration have demonstrated limited long-term efficacy and often do not address the underlying causes of the disease. On the other hand, orthobiologics are regenerative agents derived from the patient's own tissue and represent a promising emerging therapy for degenerative disc disease. This review comprehensively outlines the pathophysiology of DDD, highlighting the inadequacies of existing pharmacological therapies and detailing the potential of orthobiologic approaches. It explores advanced tools such as platelet-rich plasma and mesenchymal stem cells, providing a historical overview of their development within regenerative medicine, from foundational in vitro studies to preclinical animal models. Moreover, the manuscript delves into clinical trials that assess the effectiveness of these therapies in managing DDD. While the current clinical evidence is promising, it remains insufficient for routine clinical adoption due to limitations in study designs. The review emphasizes the need for further research to optimize these therapies for consistent and effective clinical outcomes, potentially revolutionizing the management of DDD and offering renewed hope for patients.

Leukoreduced PRP enhanced proliferation and ECM production yet inhibited senescence, inflammation, and multi-differentiation potential of AFSCs by downregulating HMGB1

BACKGROUND

This study assessed the role and potential mechanism of platelet-rich plasma (PRP) in the progression of intervertebral disk degeneration (IVDD).

METHODS

Annulus fibrosus (AF)-derived stem cells (AFSCs) from New Zealand white rabbits received the transfection with high mobility group box 1 (HMGB1) plasmids and the subsequent treatment with bleomycin, 10% leukoreduced PRP or leukoconcentrated PRP. Dying cells were indicated by immunocytochemistry analysis for senescence-associated β-galactosidase (SA-β-gal) staining. The proliferation of these cells was evaluated based on the population doubling time (PDT). The expressions of HMGB1, pro-aging and anti-aging molecules, extracellular matrix (ECM)-related catabolic/anabolic factors, and inflammatory genes at the molecular or transcriptional levels were quantified via Western blot or reverse transcription-quantitative PCR (RT-qPCR). Besides, the adipocytes, osteocytes, and chondrocytes were separately dyed by Oil Red O, Alizarin Red S, and Safranin O staining.

RESULTS

Bleomycin enhanced the senescent morphological changes and increased the PDT and the expressions of SA-β-gal, pro-aging molecules, ECM-related catabolic factors, inflammatory genes, and HMGB1 while suppressing the expressions of anti-aging and anabolic molecules. Leukoreduced PRP reversed the effects of bleomycin and inhibited the differentiation of AFSCs into adipocytes, osteocytes, and chondrocytes. Besides, HMGB1 overexpression offset the roles of leukoreduced PRP in AFSCs.

CONCLUSION

Leukoreduced PRP promotes cell proliferation and ECM production of AFSCs, while inhibiting their senescence, inflammation, and multi-differentiation potentials via downregulating HMGB1 expression.

A Review: Methodologies to Promote the Differentiation of Mesenchymal Stem Cells for the Regeneration of Intervertebral Disc Cells Following Intervertebral Disc Degeneration

Intervertebral disc (IVD) degeneration (IDD), a highly prevalent pathological condition worldwide, is widely associated with back pain. Treatments available compensate for the impaired function of the degenerated IVD but typically have incomplete resolutions because of their adverse complications. Therefore, fundamental regenerative treatments need exploration. Mesenchymal stem cell (MSC) therapy has been recognized as a mainstream research objective by the World Health Organization and was consequently studied by various research groups. Implanted MSCs exert anti-inflammatory, anti-apoptotic, and anti-pyroptotic effects and promote extracellular component production, as well as differentiation into IVD cells themselves. Hence, the ultimate goal of MSC therapy is to recover IVD cells and consequently regenerate the extracellular matrix of degenerated IVDs. Notably, in addition to MSC implantation, healthy nucleus pulposus (NP) cells (NPCs) have been implanted to regenerate NP, which is currently undergoing clinical trials. NPC-derived exosomes have been investigated for their ability to differentiate MSCs from NPC-like phenotypes. A stable and economical source of IVD cells may include allogeneic MSCs from the cell bank for differentiation into IVD cells. Therefore, multiple alternative therapeutic options should be considered if a refined protocol for the differentiation of MSCs into IVD cells is established. In this study, we comprehensively reviewed the molecules, scaffolds, and environmental factors that facilitate the differentiation of MSCs into IVD cells for regenerative therapies for IDD.

Self-assembling peptides with hBMP7 biological activity promote the differentiation of ADSCs into nucleus pulposus-like cells

Functionalized self-assembling peptides, which display functional growth-factor bioactivity, can be designed by connecting the C-terminus of a pure self-assembling peptide with a short functional motif. In this study, we designed a novel functionalized peptide (RADA16-SNVI) in which an SNVI motif with hBMP-7 activity was conjugated onto the C-terminus of the RADA16 peptide via solid-phase synthesis. A mix of RADA16-SNVI and RADA16 solutions was used to create a functionalized peptide nanofiber scaffold (SNVI-RADA16). The hydrogels were analyzed by atomic force microscopy, circular dichroism, and scanning electron microscopy. The results showed that the SNVI-RADA16 solution effectively formed hydrogel. Next, we seeded the SNVI-RADA16 scaffold with adipose-derived stem cells (ADSCs) and investigated whether it displayed biological properties of nucleus pulposus tissue. SNVI-RADA16 displayed good biocompatibility with the ADSCs and induced their expression. Cells in SNVI-RADA16 gel had a greater secretion of the extracellular matrix marker collagen type II and aggrecan compared to ADSCs grown in monolayer and control gel (p < 0.05). The ratio of the aggrecan to collagen in cells in SNVI-RADA16 gel is approximately 29:1 after culture for 21 days. ADSCs in SNVI-RADA16 gels expressed the hypoxia-inducible factor 1α(HIF-1α) mRNA by real-time PCR. However, HIF-1 mRNA is absence in control gel and monolayer. The results suggested that the functionalized self-assembled peptide promotes the differentiation of ADSCs into nucleus pulposus-like cells. Thus, the designed SNVI-RADA16 self-assembling peptide hydrogel scaffolds may be suitable for application in nucleus pulposus tissue regeneration.

Effect of Platelet-Rich Plasma on Intervertebral Disc Degeneration In Vivo and In Vitro: A Critical Review

Intervertebral disc degeneration (IDD) is a globally occurring disease that represents a significant cause of socioeconomic problems. Currently, the main method for treating IDD is surgery, including discectomy and vertebral fusion. Several in vitro experiments demonstrated that platelet-rich plasma (PRP) could stimulate cell proliferation and extracellular matrix regeneration. Additionally, in vivo experiments have proven that PRP injection could restore intervertebral disc height. Clinical studies demonstrated that PRP injection could significantly relieve patient pain. However, further studies are still required to clarify the roles of PRP in IDD prevention and treatment. This review is aimed at summarizing and critically analyzing the current evidence regarding IDD treatment with PRP.

Use of Platelet-Rich Plasma in Treating Low Back Pain: A Review of the Current Literature

Low back pain (LBP) is a common problem encountered by physicians. It is a considerable cause of morbidity and socioeconomic loss and is one of the most expensive musculoskeletal disorders. Conventional treatments include bed rest, analgesics, therapeutic exercises, lumbar or caudal epidural corticosteroids, and surgery. Several new biological therapies are being investigated for use in LBP and one of these is platelet-rich plasma (PRP). In this article, we summarize the current literature published on PRP concerning its composition, classification, and application in LBP. We believe our review will prove useful to clinicians and academics alike, interested in new developing therapies for LBP.

Platelet-rich plasma in the management of chronic low back pain: a critical review

Low back pain (LBP) is now regarded as the first cause of disability worldwide and should be a priority for future research on prevention and therapy. Intervertebral disc (IVD) degeneration is an important pathogenesis of LBP. Platelet-rich plasma (PRP) is an autologous blood concentrate that contains a natural concentration of autologous growth factors and cytokines and is currently widely used in the clinical setting for tissue regeneration and repair. PRP has great potential to stimulate cell proliferation and metabolic activity of IVD cells in vitro. Several animal studies have shown that the injection of PRP into degenerated IVDs is effective in restoring structural changes (IVD height) and improving the matrix integrity of degenerated IVDs as evaluated by magnetic resonance imaging (MRI) and histology. The results of this basic research have shown the great possibility that PRP has significant biological effects for tissue repair to counteract IVD degeneration. Clinical studies for evaluating the effects of the injection of PRP into degenerated IVDs for patients with discogenic LBP have been reviewed. Although there was only one double-blind randomized controlled trial, all the studies reported that PRP was safe and effective in reducing back pain. While the clinical evidence of tissue repair of IVDs by PRP treatment is currently lacking, there is a great possibility that the application of PRP has the potential to lead to a feasible intradiscal therapy for the treatment of degenerative disc diseases. Further large-scale studies may be required to confirm the clinical evidence of PRP for the treatment of discogenic LBP.

Biomechanical, structural and biological characterisation of a new silk fibroin scaffold for meniscal repair

Meniscal injury is typically treated surgically via partial meniscectomy, which has been shown to cause cartilage degeneration in the long-term. Consequently, research has focused on meniscal prevention and replacement. However, none of the materials or implants developed for meniscal replacement have yet achieved widespread acceptance or demonstrated conclusive chondroprotective efficacy.

A redesigned silk fibroin scaffold, which already displayed promising results regarding biocompatibility and cartilage protection in a previous study, was characterised in terms of its biomechanical, structural and biological functionality to serve as a potential material for permanent partial meniscal replacement. Therefore, different quasi-static but also dynamic compression tests were performed. However, the determined compressive stiffness (0.56 ± 0.31 MPa and 0.30 ± 0.12 MPa in relaxation and creep configuration, respectively) was higher in comparison to the native meniscal tissue, which could potentially disturb permanent integration into the host tissue. Nevertheless, µ-CT analysis met the postulated requirements for partial meniscal replacement materials in terms of the microstructural parameters, like mean pore size (215.6 ± 10.9 µm) and total porosity (80.1 ± 4.3%). Additionally, the biocompatibility was reconfirmed during cell culture experiments. The current study provides comprehensive mechanical and biological data for the characterisation of this potential replacement material. Although some further optimisation of the silk fibroin scaffold may be advantageous, the silk fibroin scaffold showed sufficient biomechanical competence to support loads already in the early postoperative phase.

Biologic therapies to enhance intervertebral disc repair

Degenerative disc disease is a progressive, chronic disorder with strong association to pain, where the dysregulated tissue environment signals disc cells, thereby leading to a low inflammatory process and slow extracellular matrix degradation and fibrosis in a perpetual vicious cycle, generating a structural and functional failure of intervertebral disc joint (IVDJ). Among current biologic therapies, there is an emerging minimally invasive strategy that consists of infiltrating plasma rich in growth factors, a safe and efficacious therapeutic approach for other musculoskeletal degenerative conditions. This review summarizes the homeostasis and degeneration of IVDJ, discusses some results on basic science and therapeutic use of platelet-rich plasma products and advances an alternative minimally invasive biologic therapy in IVDJ degeneration and chronic back pain.

Efficacy of Platelet-Rich Plasma in Retarding Intervertebral Disc Degeneration: A Meta-Analysis of Animal Studies

Objectives

Several animal studies have demonstrated the positive effects of platelet-rich plasma (PRP) on disc degeneration retardation. The present meta-analysis was to verify the efficacy of PRP in retarding disc degeneration in animal.

Methods

Relevant studies were identified and evaluated according to our inclusion and exclusion criteria. The standardized mean difference (SMD) and related 95% confidence interval (95% CI) were estimated to assess PRP efficiency.

Results

In total, eleven studies were included in this meta-analysis. Significant differences were found in the PRP treatment group, which showed increased disc height (SMD = 2.66, 95% CI: 1.86, 3.47, p = 0.000), increased MRI T2 signal intensity (SMD = −3.29, 95% CI: −4.44, −2.13, p = 0.000), and decreased histological degeneration grade (SMD = −4.28, 95% CI: −5.26, −3.30, p = 0.000). However, no significant increase in collagen II expression was found (SMD = 25389.74, 95% CI: −27585.72, 78365.21, p = 0.348). Apart from the subgroup analysis of the disc height based on animal species (pig) and disc degeneration model (chymopapain induction), other subgroup analysis based on animal species (rabbit and rat), study design, disc degeneration model, and follow-up period demonstrated that PRP treatment can significantly restore disc height and increase MRI T2 signal intensity.

Conclusions

PRP treatment is potentially effective in restoring disc height of rodent rabbit and rat, reducing histological degeneration grade, and increasing MRI T2 image signal. PRP injection may be promising therapy for retarding disc degeneration.

Electrospun scaffold containing TGF-β1 promotes human mesenchymal stem cell differentiation towards a nucleus pulposus-like phenotype under hypoxia

The study was aimed at evaluating the effect of electrospun scaffold containing TGF-β1 on promoting human mesenchymal stem cells (MSCs) differentiation towards a nucleus pulposus-like phenotype under hypoxia. Two kinds of nanofibrous scaffolds containing TGF-β1 were fabricated using uniaxial electrospinning (Group I) and coaxial electrospinning (Group II). Human MSCs were seeded on both kinds of scaffolds and cultured in a hypoxia chamber (2% O2), and then the scaffolds were characterised. Cell proliferation and differentiation were also evaluated after 3 weeks of cell culture. Results showed that both kinds of scaffolds shared similar diameter distributions and protein release. However, Group I scaffolds were more hydrophilic than that of Group II. Both kinds of scaffolds induced the MSCs to differentiate towards the nucleus pulposus-type phenotype in vitro. In addition, the expression of nucleus pulposus-associated genes (aggrecan, type II collagen, HIF-1α and Sox-9) in Group I increased more than that of Group II. These results indicate that electrospinning nanofibrous scaffolds containing TGF-β1 supports the differentiation of MSCs towards the pulposus-like phenotype in a hypoxia chamber, which would be a more appropriate choice for nucleus pulposus regeneration.

What is the preclinical evidence on platelet rich plasma and intervertebral disc degeneration?

PURPOSE

Intervertebral disc degeneration is a common disease that usually starts from the third decade of life and it represents a significant cause of socio-economic problems. The accepted surgical treatment for disc degeneration is disc removal and vertebral fusion or, in selected cases, intervertebral disc arthroplasty. Several studies have demonstrated the ability of platelet rich plasma (PRP) to stimulate cell proliferation and extracellular matrix regeneration. However, literature results are still limited and more studies are required to clarify the role of PRP in the prevention or in the treatment of degenerative disc disease. The aim of this review is to summarize and critically analyze the current preclinical evidence about the use of PRP in intervertebral disc degeneration.

METHODS

Literature search was performed through various combinations of the following keywords: Intervertebral Disc Degeneration, Platelet Rich Plasma, PRP, Intervertebral disc regeneration. Papers included in our review cover the period between 2006 and 2014. The PRISMA 2009 checklist was followed.

RESULTS

At the end of the review process, 12 articles were included in our final manuscript, including 6 "in vitro" and 6 "in vivo" studies. All the included studies lead to positive preclinical results. No standardization of methodological analysis was observed.

CONCLUSION

It is not possible to draw definitive evidence about the use of PRP in IVD regeneration. We advise a proper standardization of the methodological analysis in order to compare the available data and achieve definitive results. This should be the cornerstone for future clinical applications.

Alkaline phosphatase expression/activity and multilineage differentiation potential are the differences between fibroblasts and orbital fat-derived stem cells--a study in animal serum-free culture conditions

Human orbital fat tissues are a potential source to isolate stem cells for the development of regenerative medicine therapies. For future safe clinical application of these cells, it is critical to establish animal component-free culture conditions as well as to clearly define the stem cell population characteristics differentiating them from other cell types, such as fibroblasts. Therefore, the present study aimed to compare phenotypic and functional characteristics of orbital fat-derived stem cells (OFSCs) and fibroblasts resident in the eyelid skin in donor-matched samples grown in culture medium supplemented with pooled allogeneic human serum (HS) replacing fetal bovine serum (FBS). We first investigated the proliferative effects of OFSCs on HS, and then we compared the alkaline phosphatase (AP) expression and activity, immunophenotypic profile, and in vitro multilineage differentiation potential of OFSCs side-by-side with fibroblasts. The results showed that HS enhanced OFSCs proliferation without compromising their immunophenotype, AP activity, and osteogenic, adipogenic, and chondrogenic differentiation capacities. In contrast to OFSCs, the fibroblasts did not exhibit AP expression and activity and did not have multilineage differentiation potential. The results enabled us to successfully distinguish OFSCs from fibroblasts populations, suggesting that AP expression/activity and multilineage differentiation assays can be used reliably to discriminate mesenchymal stem cells from fibroblasts. Our findings also support the feasibility of pooled allogeneic HS as a safer and more effective alternative to FBS for clinical applications.

Comprehensive study of hydrostatic pressure treated human umbilical cord blood cells via response surface method

Amelioration of the survival parameters of cryopreserved samples after thawing has already been addressed through several techniques including vitrification to avoid the formation of ice cores. However, this approach cannot be followed in the case of samples with higher volumes. Hydrostatic pressure (HP) treatment has been proven to increase some qualifying parameters (e.g., motility, insemination efficiency) of certain biological samples. Accordingly, the preparation of umbilical cord blood (UCB) samples through an active (mechanical) pre-stressing process to increase the survival rate of cryopreserved samples can be regarded as a novel strategy that calls for basic experimental studies. The goal of our study was to assess the effects of HP treatment on the qualifying parameters (DNA fragmentation by agarose gel electrophoresis and capillary electrophoresis, Total Nucleotide Cell (TNC) count, CD34+/CD45+ count, and superoxide dismutase activity (SOD) of human umbilical cord blood (UCB) derived cells). The experimental arrangement was set to provide data for response-surface analysis to take into account the common effects of the individual variables of pressure and time exposure. 3D visualization of experimental data revealed that 50-min long HP treatment at 12.5 MPa can significantly (α = 0.05) enhance white blood cell (WBC) and CD34+/CD45+ cell counts. However no DNA fragmentation was observed even at higher pressures, SOD activity was triggered over 15.0 MPa. As a conclusion, HP treatment may contribute to the optimal cryopreservation of UCB cells by significantly increasing WBC and CD34+/CD45+ cell counts without adverse effects neither on DNA stability nor on triggering SOD activity.

Molecular interactions between human cartilaginous endplates and nucleus pulposus cells: a preliminary investigation

STUDY DESIGN

Conditioned media (CM) of cartilaginous endplates (CEPs) of intervertebral discs were analyzed in a bioassay with regard to their influence on matrix turnover and inflammatory factors on nucleus pulposus (NP) cells of the same patient. CEP tissue underwent further histological and ultrastructural analysis.

OBJECTIVE

To identify possible interactions between the CEP and the disc via molecular factors that may influence disc matrix degradation and to determine degenerative changes of CEP tissue.

SUMMARY OF BACKGROUND DATA

Impaired endplate perme-ability due to degeneration and calcification is considered to be a key contributor to disc degeneration. An upregulation of metalloproteinases and inflammatory cytokines has been observed in degenerated intervertebral discs. Possibly, the CEP contributes to the regulation of disc matrix degradation via molecular interactions with the disc tissue.

METHODS

CEP and NP cells from the same patients (n = 6) were investigated in a bioassay with regard to their influence on matrix turnover and inflammatory factors. We determined gene expression of NP cells in alginate beads that were exposed to CM of CEP punches (CEP-CM) from the same patients. The CEP-CMs were analyzed by protein array for inflammatory cytokines. Further CEP samples underwent histological (n = 15) and ultrastructural analysis (n = 8) to determine alterations of cell and matrix structure.

RESULTS

NP cells exposed to their donor-corresponding CEP-CM significantly upregulated interleukins (IL-6, IL-8) and matrix metalloproteinase (MMP-3, MMP-13) expression, and significantly decreased aggrecan and collagen type 2 expression. Proinflammatory cytokines were identified in the CEP-CM. The occurrence of apoptotic cells and degraded matrix fragments varied strongly between donors.

CONCLUSION

Our results indicate interactions between the CEP and the NP tissue via molecular factors that upregulate matrix degrading enzymes and inflammatory cytokines and thereby influence the pathophysiology of disc degeneration. Ongoing investigations will further identify the regulative role of potential molecular factors that are responsible for these degenerative alterations.

LEVEL OF EVIDENCE

N/A.

Injectable alginate hydrogels for cell delivery in tissue engineering

Alginate hydrogels are extremely versatile and adaptable biomaterials, with great potential for use in biomedical applications. Their extracellular matrix-like features have been key factors for their choice as vehicles for cell delivery strategies aimed at tissue regeneration. A variety of strategies to decorate them with biofunctional moieties and to modulate their biophysical properties have been developed recently, which further allow their tailoring to the desired application. Additionally, their potential use as injectable materials offers several advantages over preformed scaffold-based approaches, namely: easy incorporation of therapeutic agents, such as cells, under mild conditions; minimally invasive local delivery; and high contourability, which is essential for filling in irregular defects. Alginate hydrogels have already been explored as cell delivery systems to enhance regeneration in different tissues and organs. Here, the in vitro and in vivo potential of injectable alginate hydrogels to deliver cells in a targeted fashion is reviewed. In each example, the selected crosslinking approach, the cell type, the target tissue and the main findings of the study are highlighted.