Mesenchymal and induced pluripotent stem cells for the regenerative medicine of intervertebral disc: the REMEDIV project. – REMEDIV

The intervertebral disc (IVD) is a fibro-cartilage that plays a critical role in spinal kinematics by ensuring the function of "mechanical stress absorber." It consists of a peripheral network of collagen fibers (Annulus fibrosus) surrounding a highly hydrated gel structure (Nucleus pulposus: NP). This structure undergoes an inevitable degenerative process over time that is initiated by the alteration and dehydration of the NP. This degeneration is the probable cause of low back pain in 40% of patients making this disease a public health concern. The management of discogenic lombalgia is primarily analgesic but, may also require the use of invasive surgical procedures (spine fusion, arthroplasty) for the more advanced cases. Faced with the limitations of these therapies, and considering the recent improvement in our knowledge on cellular mechanisms that result in IVD degeneration, regenerative medicine offers new prospects for the treatment of degenerative diseases. The pivotal role of IVD cells has been highlighted and particularly the molecular dialog between nucleopulpocytes (NPCy) and notochordal cells (NTC), the two resident cell types of the NP. In this context, REMEDIV aims to propose an innovative and unique therapeutic strategy using the recent advances in the physiopathological aspects of IVD degeneration. REMEDIV project aims to mimic the NP niche by developing an injectable hybrid component containing bioactive NPCy and NTC within a hydrated biomaterial scaffold that could greatly contribute to NP regeneration.
Mesenchymal stromal cells (MSC) are a promising source of cells to generate bioactive NPCy due to their multi-lineage differentiation capacity and secretion of trophic factors. The generation of NTC remains a much greater challenge, as these cells arise from the node embryonic organizer. Given this unique lineage, generating NTC compels us to use cells that exemplify an earlier differentiation intermediate: induced pluripotent stem cells (iPSC).
This project is based on the complementarity of three academic partners located in Nantes: (i) INSERM UMRS791 (partner 1 and coordinator) specialized in skeletal tissue engineering, stem cells and biomaterials, (ii) the regional iPSC core facility (partner 2) specialized in the controlled production of iPSC, and the CRIP- ONIRIS (partner 3) specialized in the development of animal models of skeletal diseases. In a first set of experiments, we will define the culture conditions required for the generation of functional NPCy derived from human adipose MSCs (hASC) (WP1). Then, we will define the culture conditions required for generating some functional embryonic and mature NTC derived from human iPSC (hiPSC) (WP2).
We will then develop in vitro experimental organogenesis to promote the de novo formation of NP tissue by using NPCy and NTC co-cultured within an in-house patented Si-HPMC hydrogel. The in vivo effectiveness of this tissue neoformation will then be evaluated by injecting NPCy/NTC/Si-HPMC engineered constructs in nude mice subcutis (WP3).
Finally, to establish the proof of concept of using hASC/hiPSC-derived regenerative cells and injectable biomaterials for the treatment of degenerative disc disease, we will test the therapeutic efficacy of our concept in an animal model of degenerative disc disease recently developed by partners 1 and 3 in the sheep (WP4). The REMEDIV project will help us to better define the therapeutic potential of stem cells and particularly the association of hASC and hiPSC and to establish the proof of concept of using a regenerative medicine approach for the treatment of degenerative disc disease. If successful, the REMEDIV project will provide preclinical data before considering the first clinical trials in humans.