Department of Neuroscience and Rehabilitation, University of Ferrara, 44121 Ferrara, Italy.
Stem Cells and Regenerative Medicine Lab, Fondazione Istituto di Ricerca Pediatrica Città della Speranza, 35129 Padua, Italy; Department of Women's and Children's Health, University of Padova, 35127 Padua, Italy.
Life Sci. 2022 Jul 15;301:120623. doi: 10.1016/j.lfs.2022.120623. Epub 2022 May 7.
The main cause of low back pain is the intervertebral disc (IVD) degeneration. Designing an effective disc regeneration strategy still remains a major challenge, especially for the lack of effective self-healing capacity. Understanding the properties of IVD cells in the degenerate microenvironment could help to develop in situ regeneration strategies. The objective of the present study was to investigate the ability of degenerate cells to respond to conditions they experience physiologically in their niche in vivo, namely the presence of the hypoxic environment and trophic factors.
Degenerate cells from IVD of patients operated for herniated disc were exposed to hypoxic priming and decellularized Wharton's jelly matrix (DWJM) as scaffold and trophic factors source for 48 h in culture. Cell response was evaluated in terms of cell viability, proliferation, cytoskeletal organization, migratory ability and expression of discogenic transcription factors (SOX9, TRPS1), hypoxia-inducible factor 1α (HIF-1α) and longevity transcription factor FOXO3a. The recruitment of HIF-1α at FOXO3a and SOX9 gene promoters was analyzed by Chromatin immunoprecipitation.
Degenerate IVD cells were able to re-acquire the discogenic phenotype, and to re-adapt to hypoxia after exposure to hypoxic priming and DWJM. We demonstrated for the first time that HIF-1α is specifically recruited at the promoter of SOX9 and FOXO3a which are crucial for IVD homeostasis and repair.
These results open new avenues to engineer IVD by demonstrating that appropriate stimuli are able to dampen the degenerated IVD cell phenotype and to promote anabolic activity in cells which are constitutively characterized by poor reparative capacity.
腰椎间盘（IVD）退变是导致下腰痛的主要原因。设计有效的椎间盘再生策略仍然是一个主要挑战，特别是由于缺乏有效的自我修复能力。了解退变微环境中 IVD 细胞的特性有助于开发原位再生策略。本研究旨在探讨退变细胞对其在体内龛位中经历的生理条件（即缺氧环境和营养因子）的反应能力。
将因椎间盘突出症而行手术的患者的 IVD 退变细胞暴露于缺氧预刺激和去细胞化 Wharton 胶基质（DWJM）中，作为培养 48 小时的支架和营养因子来源。通过细胞活力、增殖、细胞骨架组织、迁移能力和椎间盘形成转录因子（SOX9、TRPS1）、缺氧诱导因子 1α（HIF-1α）和长寿转录因子 FOXO3a 的表达来评估细胞反应。通过染色质免疫沉淀分析，研究了 HIF-1α 在 FOXO3a 和 SOX9 基因启动子上的募集情况。
退变的 IVD 细胞在经历缺氧预刺激和 DWJM 后，能够重新获得椎间盘形成表型，并重新适应缺氧环境。我们首次证明，HIF-1α 特异性募集到 SOX9 和 FOXO3a 的启动子上，这对于 IVD 的内稳态和修复至关重要。
这些结果为通过证明适当的刺激能够抑制退变的 IVD 细胞表型，并促进固有修复能力差的细胞的合成代谢活性，为工程 IVD 开辟了新途径。
