Micro Fragmented Adipose Tissue Promotes the Matrix Synthesis Function of Nucleus Pulposus Cells and Regenerates Degenerated Intervertebral Disc in a Pig Model

Abstract

Intervertebral disc (IVD) degeneration and consequent lower back pain is a common disease. Micro fragmented adipose tissue (MFAT) is promising for a wide range of applications in regenerative medicine. In this study, MFAT was isolated by a nonenzymatic method and co-cultured with nucleus pulposus cells (NPCs) using an indirect co-culture system in vitro. A pig disc degeneration model was used to investigate the regenerative effect of MFAT on degenerated IVDs in vivo. The mRNA expression of Sox9, Acan, and Col2 in NPCs was significantly increased, while no significant increase was observed in the mRNA expression of proinflammatory cytokine genes after the NPCs were co-cultured with MFAT. Nucleus pulposus (NP)-specific markers were increased in MFAT cells after co-culture with NPCs. After injection of MFAT, the disc height, water content, extracellular matrix, and structure of the degenerated NP were significantly improved. MFAT promoted the matrix synthesis function of NPCs, and NPCs stimulated the NP-like differentiation of MFAT cells. In addition, MFAT also partly regenerated degenerated IVDs in the pig model.

Cell sources proposed for nucleus pulposus regeneration

“…Isolated hADMSC grow as adherent monolayers with a spindle-shaped and fibroblast-like morphology in vitro [219][220][221] and exhibit high proliferation capability in appropriate culture conditions. 220,222 When maintained in standard culture conditions hADMSC expressed mesenchymal stem cell markers CD73, CD90, and CD105, and lacked expression of hematopoietic cell markers CD14, CD34, and CD45, and the immunological cell markers CD19 and HLA-DR. 224,226 Similar to BMSC, these cells have the ability to differentiate into osteogenic, chondrogenic and adipogenic lineages. 220,[222][223][224]…”

“…220,222 When maintained in standard culture conditions hADMSC expressed mesenchymal stem cell markers CD73, CD90, and CD105, and lacked expression of hematopoietic cell markers CD14, CD34, and CD45, and the immunological cell markers CD19 and HLA-DR. 224,226 Similar to BMSC, these cells have the ability to differentiate into osteogenic, chondrogenic and adipogenic lineages. 220,[222][223][224]…”

“…199 In degenerated IVD models in vivo hADMSC have been observed after 2 weeks, 229 10 weeks, 190 and 12 weeks post-injection 220 in small animal models and 16 weeks in Porcine animal model. 222 ‡ ‡ ‡ ‡ ‡ ‡ 11.3 | Regenerative effect of adipose derived stromal cells hADMSC have been studied in small animal models, using genetically defective biglycan mice, 220 rats and rabbit models subject to needle puncture injury, 190,[230][231][232] in one large animal model 222 and in a human clinical trial. 223 hADMSC diffused throughout the IVDs.…”

Animal models of regenerative medicine for biological treatment approaches of degenerative disc diseases

“…Cell transplantation, gene therapy, application of bioactive factors, and bioscaffolds have been used for in vivo therapy approaches in porcine models of disc degeneration. Bone marrow-derived autologous, allogeneic or xenogenic (human derived) MSCs, ADSCs, iPSCs, and chondrocytes have been implanted with or without gene modification or in combination with bioscaffolds 107–117 (Table 7). To achieve anterior intradiscal fusion in porcine model of disc degeneration using minimally invasive techniques, autologous MSCs that were transduced with AdV-BMP2 were used.…”

“…The results verified that MFAT could promote the function of NPCs and NPCs could stimulate the NP-like differentiation of ADSCs. 113 Furthermore, iPSCs generated from normal human dermal fibroblasts and co-cultured with MSCs in hypoxic condition (2% O 2 ) and defined growth media for differentiation towards notochordal-like cells (NCs) were used in a porcine model of disc degeneration. The co-cultured iPSCs or MSCs alone (1 × 10 6 cells) suspended in 100 µL hydrogel (Geltrex™) or hydrogel alone were injected into lumbar discs at four weeks after anular puncture injury.…”