Immunosuppressed Miniswine as a Model for Testing Cell Therapy Success: Experience With Implants of Human Salivary Stem/Progenitor Cell Constructs

Abstract

An urgent need exists to develop large animal models for preclinical testing of new cell therapies designed to replace lost or damaged tissues. Patients receiving irradiation for treatment of head and neck cancers frequently develop xerostomia/dry mouth, a condition that could one day be treated by cell therapy to repopulate functional saliva-producing cells. Using immunosuppression protocols developed for patients receiving whole face transplants, we successfully used immunosuppressed miniswine as a suitable host animal to evaluate the long-term stability, biocompatibility, and fate of matrix-modified hyaluronate (HA) hydrogel/bioscaffold materials containing encapsulated salivary human stem/progenitor cells (hS/PCs). An initial biocompatibility test was conducted in parotids of untreated miniswine. Subsequent experiments using hS/PC-laden hydrogels were performed in animals, beginning an immunosuppression regimen on the day of surgery. Implant sites included the kidney capsule for viability testing and the parotid gland for biointegration time periods up to eight weeks. No transplant rejection was seen in any animal assessed by analysis of the tissues near the site of the implants. First-generation implants containing only cells in hydrogel proved difficult to handle in the surgical suite and were modified to adhere to a porcine small intestinal submucosa (SIS) membrane for improved handling and could be delivered through the da Vinci surgical system. Several different surgical techniques were assessed using the second-generation 3D-salivary tissue (3D-ST) for ease and stability both on the kidney capsule and in the capsule-less parotid gland. For the kidney, sliding the implant under the capsule membrane and quick stitching proved superior to other methods. For the parotid gland, creation of a tissue “pocket” for placement and immediate multilayer tissue closure were well tolerated with minimal tissue damage. Surgical clips were placed as fiduciary markers for tissue harvest. Some implant experiments were conducted with miniswine 90 days post-irradiation when salivation decreased significantly. Sufficient parotid tissue remained to allow implant placement, and animals tolerated immunosuppression. In all experiments, viability of implanted hS/PCs was high with clear signs of both vascular and nervous system integration in the parotid implants. We thus conclude that the immunosuppressed miniswine is a high-value emerging model for testing human implants prior to first-in-human trials.

Fabrication of polycaprolactone electrospun fibres with retinyl acetate for antioxidant delivery in a ROS-mimicking environment

“…Future work should include testing the scaffolds with other cell types—including healthy cells and primary cells which, if successful, will provide evidence in support of an in vivo study. Mouse models are extensively used in the salivary gland field ( Nam et al, 2019 ), and mini-pigs are becoming an increasingly popular model due to their comparative similarity to human anatomy ( Wu et al, 2021 ).…”

Effect of Echinochrome A on Submandibular Gland Dysfunction in Ovariectomized Rats

“…A reduction in salivary gland function after menopause has been linked to ferroptosis [9]. Ferroptosis is programmed cell death caused by iron-dependent ROS and lipid accumulation, thereby promoting lipid peroxidation [35,36]. Excessive lipid peroxidation plays a significant role in promoting ferroptosis.…”

Hydrogels for the treatment of oral and maxillofacial diseases: current research, challenges, and future directions

“…The hS/PC-HA hydrogel was inserted under the renal capsule of immunosuppressed miniswine and exposed to a single radical fraction of 15 Gy. Viability studies demonstrated that hS/PCs were still viable at least 8 weeks post-implant, producing α-amylase and expressing significant initiation of bio-integration without obvious signs of rejection or host immune response 227 . Hydrogel scaffolds can also promote secretory function of irradiated salivary glands in vivo.…”

“…Viability studies demonstrated that hS/PCs were still viable at least 8 weeks post-implant, producing α-amylase and expressing significant initiation of bio-integration without obvious signs of rejection or host immune response. 227 Hydrogel scaffolds can also promote the secretory function of irradiated salivary glands in vivo . A laminin-1 peptides (A99, YIGSR)-modified fibrin hydrogel was injected into irradiated salivary glands, and exhibited promotion of formation of functional salivary tissue.…”