Int J Biol Sci 2022; 18(9):3676-3696. doi:10.7150/ijbs.70903 This issue

Research Paper

Spheroid Formation Enhances the Regenerative Capacity of Nucleus Pulposus Cells via Regulating N-CDH and ITGβ1 Interaction

Yiyang Wang1,2, Haoming Wang2,3, Yunyun Zhuo1,2, Yanzhu Hu1,2, Xiaoxiao Li1,2, Yanqin Xu4, Biemin Sun4, Min Liu4, Luetao Zou1,2, Liehua Liu1, Lei Luo1, Chen Zhao1, Pei Li1,2,✉, Qiang Zhou1,2,✉

1. Department of Orthopedics, The Third Affiliated Hospital of Chongqing Medical University, Chongqing 401120, China
2. Tissue Repairing and Biotechnology Research Center, The Third Affiliated Hospital of Chongqing Medical University, Chongqing 401120, China
3. Department of Orthopedics, Three Gorges Central Hospital of Chongqing University, Chongqing 404000, China
4. College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China

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Citation:
Wang Y, Wang H, Zhuo Y, Hu Y, Li X, Xu Y, Sun B, Liu M, Zou L, Liu L, Luo L, Zhao C, Li P, Zhou Q. Spheroid Formation Enhances the Regenerative Capacity of Nucleus Pulposus Cells via Regulating N-CDH and ITGβ1 Interaction. Int J Biol Sci 2022; 18(9):3676-3696. doi:10.7150/ijbs.70903. Available from https://www.ijbs.com/v18p3676.htm

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Abstract

Graphic abstract

Background: Nucleus pulposus (NP) degeneration is the core pathological change of intervertebral disc (IVD) degenerative diseases, but currently, no effective therapy is available. With the rapid development of biomaterials and tissue engineering in recent years, biomaterial-assisted cell transplantation becomes a promising therapy for IVD degeneration. However, the application is severely limited by the weak biological characteristics of NP cells (NPCs), such as a moderate proliferation ability, weak self-renewal capacity, and minimal extracellular matrix (ECM) synthesis capacity, caused by the current inappropriate cell seeding or grafting methods.

Methods: Here, we developed a three-dimensional (3D) spheroidizing culture method to construct NPC spheroids and investigated repair and regeneration potential of these spheroids in vitro and in vivo. The in vitro biological characteristics (including cell viability and proliferation), and in vivo functions (including anti-degeneration potential and ability to induce tissue repair) of NPC spheroids and monolayer-cultured NPCs were compared. Furthermore, an RNA-seq-based transcriptome analysis and a series of function experiments were performed to elucidate the potential mechanisms of their differences that were involved in the tissue regeneration process.

Results: NPC spheroids exhibited obviously superior self-renewal and ECM synthesis capacities compared to monolayers of NPCs in vitro. In vivo, NPC spheroids generated more functional ECM components, primarily aggrecan (ACAN) and collagen type II (Col2), and markedly promoted NP regeneration in the disc degeneration model induced by partial NP excision. Additionally, the biological characteristics and functions of NPC spheroids were to some extent regulated by the interaction of N-cadherin (N-CDH) and Integrinβ1 (ITGβ1), two key mechanosensing ECM-receptors expressed on NPCs.

Conclusions: The NPC spheroidizing culture method is beneficial for cell renewal and the generation of functional ECM in NP tissue. The molecular mechanism involved in this regeneration process is closely associated with the regulation of the N-CDH and ITGβ1 interaction-mediated ECM homeostesis. Moreover, the strategy of hydrogel-assisted NPC spheroids transplantation may potentially be used in the future treatment of IVD degeneration.

Keywords: Nucleus pulposus cell (NPC), extracellular matrix (ECM), tissue regeneration, microtissue, hydrogel