Biomimetic nucleus pulposus scaffold created from bovine caudal intervertebral disc tissue utilizing an optimal decellularization procedure

Abstract

Intervertebral disc (IVD) degeneration (IDD) and herniation (IDH) can result in low back pain and impart significant socioeconomic burden. These pathologies involve detrimental alteration to the nucleus pulposus (NP) either via biochemical degradation or extrusion from the IVD, respectively. Thus, engineering living NP tissue utilizing biomaterial scaffolds that recapitulate native NP microarchitecture, biochemistry, mechanical properties and which support cell viability represents an approach to aiding patients with IDD and IDH. To date, an ideal biomaterial to support NP regeneration has yet to be developed; however, one promising approach to generating biomimetic materials is to employ the decellularization (decell) of xenogeneic NP tissue to remove host DNA while maintaining critical native extracellular matrix (ECM) components. Herein, 13 different procedures were evaluated in an attempt to decell bovine caudal IVD NP tissue. An optimal method was identified which was confirmed to effectively remove bovine DNA, while maintaining physiologically relevant amounts of glycosaminoglycan (GAG) and type-II collagen. Unconfined static and dynamic compressive mechanical properties of scaffolds approached values reported for human NP and viability of human amniotic stem cells (hAMSCs) was maintained on non-crosslinked and EDC/NHS treated scaffolds for up to 14 days in culture. Taken together, NP tissue obtained from bovine caudal IVDs can be successfully decelled in order to generate a biomimetic scaffold for NP tissue regeneration.

Decellularization and characterization of a whole intervertebral disk xenograft scaffold

“…45 However, the retained GAG content of the decellularized intact bovine IVDs resembles that of a mildly degenerate IVD and is comparable or greater than that found in other NP scaffolds. 22,34,46–48 Additionally, we have demonstrated via IHC and polarized light microscopy that a network of collagen type II is retained within the NP region of the decellularized IVDs similar to that found in native human NP tissue.…”

“…22,28–38 This top-down approach to scaffold development aims to minimize the possibility of immune rejection while yielding a biomimetic scaffold that can promote targeted tissue regeneration. Moreover, this approach offers several advantages compared to building scaffolds from the ground-up including; 1) obtaining a ‘pre-fabricated,’ tissue-specific micro-architecture without employing complex additive manufacturing techniques, which 2) yields scaffolds that provide ‘built-in’ instructional cues to local/seeded cells instructing them to attain tissue-specific phenotypes and contribute to tissue regeneration even in the absence of other exogenous soluble growth and differentiation factors.…”

Angle-ply biomaterial scaffold for annulus fibrosus repair replicates native tissue mechanical properties, restores spinal kinematics, and supports cell viability

“…Aggressive discectomy was performed by removing 1.0 ± 0.2 mL of NP tissue through the previously formed aperture remaining after annulotomy. The repair group consisted of replacing the excised tissue with an equal volume of a biologic NPR (termed ABNP – developed and described previously by our lab [19]) prior to closure with the AFRP (n = 5; AFRP dimensions: 7 mm (L) × 7 mm (W) × 0.75 mm (T)) which was secured initially with topical adhesive prior to suturing. Suturing of the AFRP consisted four corner suturing with sutures being passed through the AFRP 1–2 mm from the edge of the AFRP with throws directed in alignment with the ±30° collagen fibrils in the AFRP such that the fibers were captured within the knot.…”

“…Surgical treatments for late-stage IVDD include spinal fusion and total disc replacement, however these methods suffer from significant drawbacks [17]. Newer technologies, including NP replacement (NPR) are being developed as interventional strategies to mitigate IVDD progression [18,19]. Such devices have not yet realized clinical utility, due in part to the lack of a mechanically robust AF repair method.…”

Critical aspects and challenges for intervertebral disc repair and regeneration—Harnessing advances in tissue engineering

“…An attractive approach consists in the generation of decellularized matrices from healthy NP. Decellularization processes obtain biomaterials that represent the native tissue microstructure and biochemistry, supporting cellular adaptation . Further preclinical studies are warranted to compare such matrices with other synthetic or natural biomaterials.…”