Equiaxial Strain Modulates Adipose-derived Stem Cell Differentiation within 3D Biphasic Scaffolds towards Annulus Fibrosus

Abstract

Recurrence of intervertebral disc (IVD) herniation is the most important factor leading to chronic low back pain and subsequent disability after discectomy. Efficacious annulus fibrosus (AF) repair strategy that delivers cells and biologics to IVD injury site is needed to limit the progression of disc degeneration and promote disc self-regeneration capacities after discectomy procedures. In this study, a biphasic mechanically-conditioned scaffold encapsulated with human adipose-derived stem cells (ASCs) is studied as a potential treatment strategy for AF defects. Equiaxial strains and frequencies were applied to ASCs-encapsulated scaffolds to identify the optimal loading modality to induce AF differentiation. Equiaxial loading resulted in 2–4 folds increase in secretion of extracellular matrix proteins and the reorganization of the matrix fibers and elongations of the cells along the load direction. Further, the equiaxial load induced region-specific differentiation of ASCs within the inner and outer regions of the biphasic scaffolds. Gene expression of AF markers was upregulated with 5–30 folds within the equiaxially loaded biphasic scaffolds compared to unstrained samples. The results suggest that there is a specific value of equiaxial strain favorable to differentiate ASCs towards AF lineage and that ASCs-embedded biphasic scaffold can potentially be utilized to repair the AF defects.

The Effect of the Repression of Oxidative Stress on Tenocyte Differentiation: A Preliminary Study of a Rat Cell Model Using a Novel Differential Tensile Strain Bioreactor

“…Other specific markers should be used in future studies. For example, type II collagen, Aggrecan, and Biglycan could be used as indicators of chondrogenic differentiation, and Scleraxis, Tenascin, and Tenomodulin could be used to confirm tenogenic differentiation [27]. Histologically, tendinopathy produces disorganized fibrillary structures of collagen and increases type III/type I collagen ratios, glycosaminoglycan deposition [28,29], and aberrant differentiation of TDCs into non-tenocytes (tissue metaplasia) [30,31,32].…”

Asperosaponin VI promotes human mesenchymal stem cell differentiation into nucleus pulposus like- cells via up-regulation of ERK1/2 and Smad2/3 signaling pathways.

“…Absorbance was converted to GAG concentrations using a calibration curve obtained using different concentrations of bovine chondroitin 4sulfate as the standard. The GAGs were normalized using the total protein in the media quanti ed at UV 280 nm using a microplate reader (Bio Tek, USA) [24].…”

Strategies for Annulus Fibrosus Regeneration: From Biological Therapies to Tissue Engineering

“…With appropriate stimulation, stem cells can be directed to differentiate toward various specific cell phenotypes. Bone marrow derived mesenchymal stem cells (MSCs) and adipose derived stem cells (ASCs) in their undifferentiated state are currently the most widely used cell types (Yañez et al, 2006 ; Elsaadany et al, 2017 ). MSCs are considered as immune-evasive and hypo-immunogenic that could be transplanted across major histocompatibility barriers.…”

“…External mechanical stimuli also influence the growth of cells and formation of ECM. Elsaadany et al applied varying magnitudes of equiaxial strain at different frequencies to investigate the differentiation of ASCs (Elsaadany et al, 2017 ). They found that 6% strain and 1 Hz was the optimal loading modality to induce differentiation into AF-like cells and formation of AF-like matrix.…”