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

Abstract

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.

Hydrogel-Based Strategies for Intervertebral Disc Regeneration: Advances, Challenges and Clinical Prospects

“…Yan et al and Ying et al have characterized synthetic hydrogels as three-dimensional network microstructures that are formed by the combination of hydrophilic molecules that initiate a sequence of complete hydration and swelling [12,26]. These biomaterials vary in their composition and include substances (or derivatives of these substances) such as polyacrylic acid, polyacrylic acid salts, polyacrylamide derivatives, and polyvinyl oxide, to name a few [12,26]. Synthetic hydrogels have the advantage of being able to overcome the often-insufficient mechanical properties of natural hydrogels [12,26].…”

“…These biomaterials vary in their composition and include substances (or derivatives of these substances) such as polyacrylic acid, polyacrylic acid salts, polyacrylamide derivatives, and polyvinyl oxide, to name a few [12,26]. Synthetic hydrogels have the advantage of being able to overcome the often-insufficient mechanical properties of natural hydrogels [12,26]. Despite this major advantage, synthetic hydrogels also have several limitations that include the addition of potentially toxic components in the process of preparation, generally slower degradation, and often insufficient native biologic activity [12,26].…”

“…Synthetic hydrogels have the advantage of being able to overcome the often-insufficient mechanical properties of natural hydrogels [12,26]. Despite this major advantage, synthetic hydrogels also have several limitations that include the addition of potentially toxic components in the process of preparation, generally slower degradation, and often insufficient native biologic activity [12,26]. Consequently, synthetic hydrogels are rarely used alone in tissue engineering, and are instead utilized in conjunction with natural hydrogels to formulate a robust and optimal replacement biomaterial [12,26].…”

“…Polymer was designed to mimic slow degradation under physiological conditions to promote a slow replacement of hydrogel with newly deposited matrix within the IVD, as NP matrix turnover takes months to years. [26,33] Alternatively, natural hydrogels are usually derived from animal and plant extracts. According to Yan et al and Ying et al, commonly used natural hydrogels include gelatin, collagen, fibrin, hyaluronate, alginate, agarose, and chitosan [12,26].…”

“…[26,33] Alternatively, natural hydrogels are usually derived from animal and plant extracts. According to Yan et al and Ying et al, commonly used natural hydrogels include gelatin, collagen, fibrin, hyaluronate, alginate, agarose, and chitosan [12,26]. Due to their derivation from naturally occurring extracts, these hydrogels are nontoxic, have a high degree of biologic safety, and possess a high level of biocompatibility, allowing for a more natural integration into patients that receive these as a replacement [12,26].…”