Ghavimi, S. A. A. | bioRxiv Science

bioRxiv2022

Controlled Hydrogen Sulfide Delivery to Enhance Cell Survival in Bone Tissue Engineering

The increased local concentration of calcium ions (Ca2+) and phosphate (Pi), a natural body process for bone healing and remodeling, as well as local delivery of these ions as signaling molecules by synthetic bone graft substitutes, may lead to cytotoxic ion levels that can result in Ca2+/ Pi mitochondria overload, oxidative stress, and cell death. In this research, the effect of H2S as a cytoprotective signaling molecule to increase the tolerance of mesenchymal stem cells (MSCs) in the presence of cytotoxic level of Ca2+/Pi was evaluated. Different concentrations of sodium hydrogen sulfide (NaSH), a fast-releasing H2S donor, were exposed to cells in order to evaluate the influence of H2S on MSC proliferation. The results suggested that a range of NaSH (i.e., 0.25 - 4 mM NaSH) was non-cytotoxic and could improve cell proliferation and differentiation in the presence of cytotoxic levels of Ca2+ (32 mM) and/or Pi (16 mM). To controllably deliver H2S over time, a novel donor molecule in thioglutamic acid (GluSH) was synthesized and evaluated for its H2S release profile. Excitingly, GluSH successfully maintained cytoprotective level of H2S over 7 days. Furthermore, MSCs exposed to cytotoxic Ca2+/Pi concentrations in the presence of GluSH were able to thrive and differentiate into osteoblasts. These findings suggest that the incorporation of a sustained H2S donor such as GluSH into CaP-based bone substitutes can facilitate considerable cytoprotection making it an attractive option for complex bone regenerative engineering applications.

bioengineering↗

bioRxiv2022

Human cartilage progenitor cells from ear, nose, rib, and joint have a robust, stable phenotype for cartilage repair

BackgroundCartilage progenitor cells (CPCs) are a small but highly proliferative cell population that resides within cartilage. Joint cartilage CPCs have a high chondrogenic potential and superior cartilage formation characteristics; however, CPCs from other cartilage sources more accessible for translation such as ear, nose, and rib are broadly unexplored. Our study illuminates the differences between CPCs from these four cartilages, their corresponding tissue chondrocyte (CC), and bone marrow-derived mesenchymal stem cell (MSC). MethodsCPCs subtypes were isolated from pediatric cartilage via fibronectin selection, immunophenotyped by flow cytometry and compared to MSCs. Trilineage differentiation capacity was assessed via histology and qRT-PCR. Next, triiodothyronine was used to hypertrophically challenge each CPC subset and their corresponding chondrocyte population. After 28 days cartilage pellets were assessed via histology, immunohistochemistry, and qRT-PCR. FindingsEach CPC subset possessed a specific immunophenotypic signature with CD56 as a potential common marker. All CPC subsets proliferated 2-fold faster than MSCs and 4-fold faster than CCs. Additionally, CPCs had a substantially reduced propensity for osteogenic differentiation and very limited adipogenic capacity by histology and gene expression. Finally, all CPC subsets resisted the hypertrophic challenge more than the corresponding chondrocyte population marked by less collagen X secretion and downregulation of hypertrophy associated genes. InterpretationCPCs represent a promising cell type for cartilage regeneration. The ease of accessibility of the ear and nose CPCs present opportunities for new translational approaches and reduced clinical timelines. FundingCHOP Research Institute, Frontier Program in Airway Disorders of CHOP, NIH (R21HL159521), NSF-GRFP (DGE-1845298)

bioengineering↗