Evaluation of Percutaneous Intradiscal Amniotic Suspension Allograft in a Rabbit Model of Intervertebral Disc Degeneration

Editorial Commentary: Amniotic Orthopaedic Biologics: There's Hope If We Avoid Hype

Amniotic products donated from mothers having live births have been in use for wound care and other medical uses for many years. Recent developments in regenerative sciences have suggested these products in solution or lyophilized forms may be useful for the treatment of inflammatory diseases such as chronic tendinopathies and osteoarthritis of joints. These products for these indications, however, are deemed human cells, tissues, or cellular or tissue-based products (otherwise known as HCTPs) in the "351" category, meaning that they need to have a biologic license to be marketed and sold in the United States, and to gain this license, one needs to go through the usual rigor of investigational new drug filing and phase 1, 2, and 3 trials to prove safety and efficacy. Although current clinical use of amniotic solution and lyophilized products is on hold through this study period, both basic science and clinical trial studies are building a convincing set of data that suggest broad possibilities for their uses in the future. To date, both animal and human studies have shown that a single injection of amniotic suspension allograft is safe, has not elicited any significant immune response, and has been shown to be effective in several prospective studies and at least one well-controlled randomized controlled human study for knee osteoarthritis when compared with both hyaluronic acid and placebo saline. Proteins in these harvested and processed tissue allografts are anti-inflammatory, anticatabolic, and proanabolic. Appropriate caution by the Food and Drug Administration in granting licenses for these indications should not dissuade basic scientists and physicians from pursuing further research into these interesting products.

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.

Update review on five top clinical applications of human amniotic membrane in regenerative medicine

Due to the increasing number of studies performed in the field of regenerative medicine during the last two decades, more analytic studies are still needed to clarify the future prospect of this area of science. The main aim of this research was to review the clinical applications of human Amniotic membrane in the field of regenerative medicine critically. Furthermore, in the light of increasing numbers of available products derived from amniotic membrane, we aimed look in depth to see whether regenerative medicine research strategies have a place in the clinical setting. More specifically, in the present study, we attempted to provide insight on developing the new indication for more research and in the next step, for market leaders companies to expand cost-effectiveness of new derived AM products. 20 companies or distributers have offered some commercial products in this field. Survey on more than 90 clinical trials in last five years showed dermatology (and more specific wound healing), orthopedic, and ophthalmology are heavily biased toward multibillion dollar industry. Moreover, urology and dentistry with fewer numbers of clinical data in comparison with the above-mentioned areas, currently are in the path of translation (especially dentistry). In addition, otolaryngology and oncology with the lowest number showed more potential of research thorough understanding the properties that will help guiding the use of AM-derived products in these two areas in future. More than 50% of clinical studies were done or are developing in USA, which have the biggest share in market products. Subsequently, China, Egypt, India, Iran, and Germany with the ongoing clinical trials in different phases may have more approved products in near future.

Sustained release of GDF5 from a designed coacervate attenuates disc degeneration in a rat model

Low back pain is often caused by intervertebral disc degeneration, which is characterized by nucleus pulposus (NP) and extracellular matrix (ECM) degeneration. Human adipose-derived stem cells (hADSCs) induced by growth and differentiation factor-5 (GDF5) can differentiate into an NP-like phenotype. Although stem cell-based therapy with prolonged exposure to growth factors is regarded as a promising treatment, the efficacy of this approach in attenuating the disc degeneration process is limited by the short lifespan of growth factors. In our study, a unique growth factor delivery vehicle composed of heparin and the synthetic polycation poly(ethylene argininylaspartate diglyceride) (PEAD) was used to sustain GDF5 release. The results showed that sustained release of GDF5 by the PEAD:heparin delivery system promoted hADSC differentiation to an NP-like phenotype in vitro. After injection of the PEAD:heparin:GDF5 delivery platform and hADSCs into intervertebral spaces of coccygeal (Co) vertebrae Co7/Co8 and Co8/Co9 of the rat, the disc height, water content, and structure of the NPs decreased more slowly than other treatment groups. This new strategy may be used as an alternative treatment for attenuating intervertebral disc degeneration with hADSCs without the need for gene therapy. STATEMENT OF SIGNIFICANCE: Low back pain is often caused by intervertebral disc degeneration, which is characterized by nucleus pulposus (NP) and extracellular matrix (ECM) degeneration. Human adipose-derived stem cells (hADSCs) induced by growth and differentiation factor-5 (GDF-5) can differentiate into an NP-like phenotype. Although stem cell-based therapy with prolonged exposure to growth factor is regarded as a promising treatment, the efficacy of this approach in the disc regeneration process is limited by the short life of growth factors. In our study, a unique growth factor delivery vehicle comprised of heparin and the synthetic polycation poly(ethylene argininylaspartate diglyceride) (PEAD) was used to sustain the release of GDF-5. Numerous groups have explored IDD regeneration methods in vitro and in vivo. Our study differs in that GDF5 was incorporated into a vehicle through charge attraction and exhibited a sustained release profile. Moreover, GDF-5 seeded coacervate combined with hADSC injection could be a minimally invasive approach for tissue engineering that is suitable for clinical application. We investigated the stimulatory effects of our GDF-5 seeded coacervate on the differentiation of ADSCs in vitro and the reparative effect of the delivery system on degenerated NP in vivo.