Intradiscal Injection of Induced Pluripotent Stem Cell-Derived Nucleus Pulposus-Like Cell-Seeded Polymeric Microspheres Promotes Rat Disc Regeneration

Abstract

Background. Cell replacement therapy is an attractive alternative for treating degenerated intervertebral discs (IVDs), which are related to the reduction of nucleus pulposus-like cells (NP-lCs) and the loss of the extracellular matrix. Induced pluripotent stem cells (iPSCs) which resemble embryonic stem cells are considered to be a potential resource for restoring NP-lCs and disc homeostasis. Here, we proposed an efficient two-step differentiation protocol of human iPSCs into NP-lCs and continuously tested their in vivo ability to regenerate IVDs. Methods. A polymeric gelatin microsphere (GM) was generated for sustained release of growth and differentiation factor-5 (GDF-5) and as a cell delivery vehicle of NP-lCs. By injecting NP-lC-seeded GDF-5-loaded GMs into the rat coccygeal intervertebral discs, the disc height and water content were examined with the molybdenum target radiographic imaging test and magnetic resonance imaging examination. Histology and immunohistochemistry results were shown with H&E, S-O-Fast Green, and immunohistochemistry staining. Results. We demonstrated that the injection of NP-lC-seeded GDF-5-loaded GMs could reverse IDD in a rat model. The imaging examination indicated that disc height recovered and water content increased. Histology and immunohistochemistry results indicated that the NP cells as well as their extracellular matrix were partially restored. Conclusions. The results suggest that NP-lC-seeded GDF-5-loaded GMs could partially regenerate degenerated intervertebral discs after transplantation into rat coccygeal intervertebral discs. Our study will help develop a promising method of stem cell-based therapy for IDD.

Ultra-purified alginate gel implantation decreases inflammatory cytokine levels, prevents intervertebral disc degeneration, and reduces acute pain after discectomy

“…In the rabbit model, the operated spine (L2/3–L4/5) was surgically harvested, and soft tissue and vertebral bone were removed from the IVDs under sterile conditions. The harvested IVDs (rat, rabbit) were fixed with 4% (w/v) paraformaldehyde for 48 h at room temperature and embedded in paraffin 21 , 22 , 31 . Transverse sections (5 μm thick) of the middle portion of the IVD were obtained.…”

Versatility of Induced Pluripotent Stem Cells (iPSCs) for Improving the Knowledge on Musculoskeletal Diseases

“…Since then, a wide variety of studies have reported the derivation of specific cell types from iPSCs, generating robust and reproducible phenotypes in vitro that reflect diseases intrinsic to the cellular level [ 35 ]. Specifically, evidence that reprogrammed cells can be differentiated into osteoblasts [ 54 , 55 , 56 ], chondrocytes [ 57 , 58 , 59 , 60 ], myoblasts [ 61 ], nucleus pulposus cells [ 47 , 48 , 49 ] and tenocytes [ 62 ] has recently impacted musculoskeletal research and changed orthopedic medicine. Nevertheless, the use of iPSCs for studying the wide variety of musculoskeletal conditions has been explored to a limited extent ( Table 1 ) in comparison with conditions affecting nervous or cardiac pathologies, even when investigating genetic disorders where symptoms affect several organs or systems [ 63 , 64 , 65 , 66 ].…”

“…In the case of degenerative disc disease, several studies have focused on the resettlement of cells that had been lost in the intervertebral disc by injecting iPSCs [ 146 ] differentiated into nucleus pulposus [ 48 ] or notochordal cells [ 147 ], with very promising outcomes. These studies used different hydrogels with and without growth factors.…”

“…Efficient and robust differentiation of iPSCs into tissue-specific cell types is crucial both for disease modeling and for regenerative medicine. Should the reader seek a more detailed explanation about iPSC differentiation protocols, please see the previously published studies on osteogenic [ 3 , 30 , 43 , 44 , 45 ], chondrogenic [ 3 , 27 , 30 , 46 ], nucleus pulposus [ 47 , 48 , 49 ] and/or myogenic [ 3 , 30 , 50 ] differentiation of iPSCs.…”

Controlled release of biological factors for endogenous progenitor cell migration and intervertebral disc extracellular matrix remodelling

“…Clinical trials in humans have revealed significant pain relief and improvement of the quality of life of patients, albeit with very few signs of IVD regeneration [14]. Thus, a number of studies have suggested therapeutic in vitro manipulation of MSCs prior to their injection, in order to generate NP-like cells, using growth factor-driven differentiation protocols [15,16]. Co-culture experiments have also been performed to evaluate the effects of injected MSCs on resident NP cells [17,18].…”