Perspectives on the Treatment of Lumbar Disc Degeneration: The Value Proposition for a Cell-Based Therapy, Immunomodulatory Properties of Discogenic Cells and the Associated Clinical Evaluation Strategy

Biological Therapeutic Modalities for Intervertebral Disc Diseases: An Orthoregeneration Network (ON) Foundation Review

Orthoregeneration is defined as a solution for orthopaedic conditions that harnesses the benefits of biology to improve healing, reduce pain, improve function, and, optimally, provide an environment for tissue regeneration. Options include drugs, surgical intervention, scaffolds, biologics as a product of cells, and physical and electromagnetic stimuli. The goal of regenerative medicine is to enhance the healing of tissue after musculoskeletal injuries as both isolated treatment and adjunct to surgical management, using novel therapies to improve recovery and outcomes. Various orthopaedic biologics (orthobiologics) have been investigated for the treatment of pathology involving the spine, including lower back pain, with or without numbness and/or dysfunction in the lower extremities, disc herniation, spinal stenosis, and spondylolisthesis. Promising and established treatment modalities include repair of the annulus fibrosis, injection of expanded or nonexpanded autologous or allogenic cells that are chondrogenic or from a stem cell lineage used to promote matrix tissue regeneration of the intervertebral disc, including nucleus pulpous cells and mesenchymal stem cells isolated from bone marrow, umbilical cord blood, or adipose tissue; and injection of platelet-rich plasma, platelet-rich fibrin, or fibrin sealant. Early clinical studies show promise for pain reduction and functional recovery. LEVEL OF EVIDENCE: Level V, expert opinion.

Unilateral biportal endoscopic transforaminal lumbar interbody fusion versus conventional interbody fusion for the treatment of degenerative lumbar spine disease: a systematic review and meta-analysis

BACKGROUND

This meta-analysis compares the efficacy of unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF) to conventional interbody fusion in lumbar degenerative diseases (LDD).

METHODS

An extensive literature search was conducted in PubMed, Web of Science, and the Cochrane Library. Research related to UBE-TLIF published up to November 2022 was reviewed. The relevant articles were selected based on inclusion and exclusion criteria, as well as an evaluation of the quality of the data extraction literature. Meta-analysis was performed using Review Manager 5.3 software.

RESULTS

This meta-analysis included six high-quality case-control trials (CCTs) involving 621 subjects. The clinical outcomes assessment showed no statistical differences in complication rates, fusion rates, leg pain VAS scores, or ODI scores. After UBE-TLIF, low back pain VAS scores were significantly improved with less intraoperative blood loss and a shorter hospital stay. A longer time was required for UBE-TLIF, however.

CONCLUSION

Despite the lack of sufficient high quality randomized controlled trials (RCTs) in this study, the results of this meta-analysis suggest that UBE-TLIF is more effective than open surgery in terms of length of stay, blood loss reduction during surgery, and improved low back pain after surgery. Nevertheless, the evidence will be supplemented in the future by more and better quality multicenter randomized controlled trials.

"Early Efficacy and Safety of Unilateral Biportal Endoscopic Lumbar Interbody Fusion Versus Minimal Invasive in the Treatment of Lumbar Degenerative Diseases"

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

To compare the early clinical efficacy and radiologic outcomes between unilateral biportal endoscopic lumbar interbody fusion (ULIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF).

SUMMARY OF BACKGROUND DATA

Along with the continuous development of endoscopic technology, the early safety and effectiveness of ULIF technology are still unknown.

MATERIALS AND METHODS

This retrospective study included 61 patients who underwent fusion surgery through ULIF or MIS-TLIF in 2021. Twenty-nine patients underwent ULIF (group A), and 32 underwent MIS-TLIF (group B). Fusion rate, bone graft volume, hidden blood loss (HBL), C-reactive protein level, operative time, Oswestry Disability Index , Visual Analog Scale score, and MacNab criteria were assessed in both groups.

RESULTS

The Visual Analog Scale score for back pain in the early postoperative period was significantly lower in group A than in group B ( P <0.05). All other clinical scores showed improvement, with no significant difference between the 2 groups ( P >0.05). There was no statistically significant difference in postoperative C-reactive protein levels and fusion rates between the 2 groups ( P >0.05). However, HBL was higher and operative time was longer in group A than in group B ( P <0.05). Most importantly, there were no statistically significant differences between groups A and B in fusion rate, length of stay and bone graft volume ( P >0.05). No serious surgical complications occurred in our study.

CONCLUSIONS

ULIF is a new option for lumbar fusion. Despite the drawbacks of longer operation time and higher HBL, ULIF may be a viable alternative to MIS-TLIF as technology advances.

A risk assessment study of SARS-CoV-2 propagation in the manufacturing of cellular products

The potential infection of cellular therapies by SARS-CoV-2 present high risks, as the target patients for these treatments are often immunocompromised or have chronic diseases associated with a higher risk of serious illness and death by COVID-19. The multicellular tropism of this virus presents challenges for the manufacturing of cell therapies, whereby the material could potentially become infected at the source or during cell processing. In this review we assess the risk of a SARS-CoV-2 propagation in cell types used to date in cellular therapies. Altogether, the risk of SARS-CoV-2 contamination of cellular products remains low. This risk should be evaluated on an individual basis, considering ACE2 and TMPRSS2 expression, existing literature regarding the susceptibility to infection, and single cell RNA sequencing data of COVID-19 patients. This analysis should ideally be performed for both the cells being manufactured and the cells used to produce the vector to ensure patient safety.

Controversies in spine research: Organ culture versus in vivo models for studies of the intervertebral disc

Intervertebral disc degeneration is a common cause of low back pain, the leading cause of disability worldwide. Appropriate preclinical models for intervertebral disc research are essential to achieving a better understanding of underlying pathophysiology and for the development, evaluation, and translation of more effective treatments. To this end, in vivo animal and ex vivo organ culture models are both widely used by spine researchers; however, the relative strengths and weaknesses of these two approaches are a source of ongoing controversy. In this article, members from the Spine and Preclinical Models Sections of the Orthopedic Research Society, including experts in both basic and translational spine research, present contrasting arguments in support of in vivo animal models versus ex vivo organ culture models for studies of the disc, supported by a comprehensive review of the relevant literature. The objective is to provide a deeper understanding of the respective advantages and limitations of these approaches, and advance the field toward a consensus with respect to appropriate model selection and implementation. We conclude that complementary use of several model types and leveraging the unique advantages of each is likely to result in the highest impact research in most instances.

Transition from static culture to stirred tank bioreactor for the allogeneic production of therapeutic discogenic cell spheres

Background

Culturing cells as cell spheres results in a tissue-like environment that drives unique cell phenotypes, making it useful for generating cell populations intended for therapeutic use. Unfortunately, common methods that utilize static suspension culture have limited scalability, making commercialization of such cell therapies challenging. Our team is developing an allogeneic cell therapy for the treatment of lumbar disc degeneration comprised of discogenic cells, which are progenitor cells expanded from human nucleus pulposus cells that are grown in a sphere configuration.

Methods

We evaluate sphere production in Erlenmeyer, horizontal axis wheel, stirred tank bioreactor, and rocking bag format. We then explore the use of ramped agitation profiles and computational fluid dynamics to overcome obstacles related to cell settling and the undesired impact of mechanical forces on cell characteristics. Finally, we grow discogenic cells in stirred tank reactors (STRs) and test outcomes in vitro (potency via aggrecan production and identity) and in vivo (rabbit model of disc degeneration).

Results

Computation fluid dynamics were used to model hydrodynamic conditions in STR systems and develop statistically significant correlations to cell attributes including potency (measured by aggrecan production), cell doublings, cell settling, and sphere size. Subsequent model-based optimization and testing resulted in growth of cells with comparable attributes to the original static process, as measured using both in vitro and in vivo models. Maximum shear rate (1/s) was maintained between scales to demonstrate feasibility in a 50 L STR (200-fold scale-up).

Conclusions

Transition of discogenic cell production from static culture to a stirred-tank bioreactor enables cell sphere production in a scalable format. This work shows significant progress towards establishing a large-scale bioprocess methodology for this novel cell therapy that can be used for other, similar cell therapies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02525-0.