Dynamic Bioreactor Culture for Infiltration of Bone Mesenchymal Stem Cells within Electrospun Nanofibrous Scaffolds for Annulus Fibrosus Repair

Ex-vivo biomechanical evaluation of the application of a novel annulus closure device to closure of annulus fibrosus

Objective

To investigate the technical feasibility of applying a simple suture guide device to close the annulus fibrosus (AF) of the intervertebral discs (IVD).

Methods

30 sheep functional discal units (FDUs) were obtained and subjected to mock discectomy. Mock sutures were performed using 3-0 non-absorbable sutures under a novel AF suture device following a suture procedure. The FDUs were compressed under axial loading at 1.8 mm/min and evaluated for Failure load (N).

Results

The failure loads of the hand stitching group (Group H) and suture device stitching group (Group S) were significantly higher than those of the control group (Group C) (p = 0.033; p < 0.001).

Conclusion

This study provides reasonable reasons to believe that the simple suture guide device described here is technically feasible for AF defect closure. It thus constitutes an encouraging proof of concept for the proposed device; however, it does not constitute a complete demonstration of the device's feasibility in the clinical setting considering that the annulus closure operation is performed ex vivo on functional spinal units, as opposed to within an environment that mimics the clinical setting. To this end, confirmatory experiments will be conducted such as more multiaxial or dynamic mechanical testing, and notably performing the surgery on sheep models instead of on ex vivo functional spinal units.

Recent advances in the repair of degenerative intervertebral disc for preclinical applications

The intervertebral disc (IVD) is a load-bearing, avascular tissue that cushions pressure and increases flexibility in the spine. Under the influence of obesity, injury, and reduced nutrient supply, it develops pathological changes such as fibular annulus (AF) injury, disc herniation, and inflammation, eventually leading to intervertebral disc degeneration (IDD). Lower back pain (LBP) caused by IDD is a severe chronic disorder that severely affects patients' quality of life and has a substantial socioeconomic impact. Patients may consider surgical treatment after conservative treatment has failed. However, the broken AF cannot be repaired after surgery, and the incidence of re-protrusion and reoccurring pain is high, possibly leading to a degeneration of the adjacent vertebrae. Therefore, effective treatment strategies must be explored to repair and prevent IDD. This paper systematically reviews recent advances in repairing IVD, describes its advantages and shortcomings, and explores the future direction of repair technology.

Application of stem cells combined with biomaterial in the treatment of intervertebral disc degeneration

As the world population is aging, intervertebral disc degeneration (IDD) is becoming a global health issue of increasing concern. A variety of disc degeneration diseases (DDDs) have been proven to be associated with IDD, and these illnesses have significant adverse effects on both individuals and society. The application of stem cells in regenerative medicine, such as blood and circulation, has been demonstrated by numerous studies. Similarly, stem cells have made exciting progress in the treatment of IDD. However, due to complex anatomical structures and functional requirements, traditional stem cell injection makes it difficult to meet people's expectations. With the continuous development of tissue engineering and biomaterials, stem cell combined with biomaterials has far more prospects than before. This review aims to objectively and comprehensively summarize the development of stem cells combined with contemporary biomaterials and the difficulties that need to be overcome.

Magnetic-driven dynamic culture promotes osteogenesis of mesenchymal stem cell

Effective nutrient transport and appropriate mechanical stimulation play important roles in production of tissue-engineered bone grafts. In this study, an experimental set-up for magnetic-driven dynamic culture of cells was designed to mimic the microenvironment of the bone tissue. Here, its ability to contribute to osteogenic differentiation was investigated by inoculating human umbilical cord mesenchymal stem cells (HUMSCs) on magnetic scaffolds. The cytocompatibility of the developed magnetic scaffolds was verified for HUMSCs. Magnetic scaffolds seeded with HUMSCs were exposed to magnetic fields. The results showed that magnetic fields did not affect cell activity and promoted HUMSCs osteogenic differentiation. The magnetic scaffolds were magnetically driven for dynamic culture in the experimental set-up to evaluate the influence of HUMSCs osteoblast differentiation. The results indicated that magnetic-driven dynamic culture increased cell alkaline phosphatase (ALP) activity (p < 0.05) and calcium release (p < 0.05) compared with static culture. The effect was demonstrated in the expression of bone-associated genes. Overall, this study showed that magnetic-driven dynamic culture is a promising tool for regenerative bone engineering.