detergent-free-decellularization-human-pancreas-for-soluble

Detergent-Free Decellularization of the Human Pancreas for Soluble Extracellular Matrix (ECM) Production

Islet transplantation (ITx) has the potential to become the standard of care in beta cell replacement medicine but its results remain inferior to those ...

Wake Forest School of Medicine

Islet transplantation (IT) has recently been shown to be a promising alternative to pancreas transplantation for reversing diabetes. IT requires the isolation of the islets from the pancreas, and these islets can be used to fabricate a bio-artificial pancreas. Enzymatic digestion is the current gold standard procedure for islet isolation but has lingering concerns. One such concern is that it has been shown to damage the islets due to nonselective tissue digestion. This chapter provides a detailed description of a nonenzymatic method that we are exploring in our lab as an alternative to current enzymatic digestion procedures for islet isolation from human and nonhuman pancreatic tissues. This method is based on selective destruction and protection of specific cell types and has been shown to leave the extracellular matrix (ECM) of islets intact, which may thus enhance islet viability and functionality. We also show that these SOS-isolated islets can be microencapsulated for transplantation.

Selective Osmotic Shock (SOS)-Based Islet Isolation for Microencapsulation.

Loss of ovarian function (e.g., due to menopause) leads to profound physiological effects in women including changes in sexual function and osteoporosis. Hormone therapies are a known solution, but their use has significantly decreased due to concerns over cardiovascular disease and certain cancers. We recently reported a tissue-engineering strategy for cell hormone therapy (cHT) in which granulosa cells and theca cells are encapsulated to mimic native ovarian follicles. cHT improved physiological outcomes and safety compared to pharmacological hormone therapies in a rat ovariectomy model. However, cHT did not achieve estrogen levels as high as ovary-intact animals. In this report, we examined if hormone secretion from cHT constructs is impacted by incorporation of bone marrow-derived mesenchymal stem cells (BMSC) since these cells contain regulatory factors such as aromatase necessary for estrogen production. Incorporation of BMSCs led to enhanced estrogen secretion in vitro. Moreover, cHT constructs with BMSCs achieved estrogen secretion levels significantly greater than constructs without BMSCs in ovariectomized rats from 70 to 90 days after implantation, while also regulating pituitary hormones. cHT constructs with BMSC ameliorated estrogen deficiency-induced uterine atrophy without hyperplasia. The results indicate that inclusion of BMSC in cHT strategies can improve performance.

Encapsulation of Mesenchymal Stem Cells in 3D Ovarian Cell Constructs Promotes Stable and Long-Term Hormone Secretion with Improved Physiological Outcomes in a Syngeneic Rat Model.

Here, we report two methods that chemically modify alginate to achieve neutral-basic pH sensitivity of the resultant hydrogel. The first method involves direct amide bond formation between alginate and 4-(2-aminoethyl)benzoic acid. The second method that arose out of the desire to achieve better control of the degradation rate of the alginate hydrogel involves reductive amination of oxidized alginate. The products of both methods result in a hydrogel vehicle for targeted delivery of encapsulated payload under physiological conditions in the gastrointestinal tract. Two-dimensional diffusion-ordered spectroscopy and internal and coaxial external nuclear magnetic resonance standards were used to establish chemical bonding and percent incorporation of the modifying groups into the alginate polymer. The hydrogel made with alginate modified by each method was found to be completely stable under acidic pH conditions while disintegrating within minutes to hours in neutral-basic pH conditions. We found that, while alginate oxidation did not affect the β-d-mannuronate/α-l-guluronate ratio of alginate, the rate of disintegration of the hydrogel made with oxidized alginate was dependent upon the degree of oxidation.

Chemical Modification of Alginate for Controlled Oral Drug Delivery.

To support the increasing translational use of transplanted cells, there is a need for high-throughput cell encapsulation technologies. Microfluidics is a particularly promising candidate technology to address this need, but conventional polydimethylsiloxane devices have encountered challenges that have limited their utility, including clogging, leaking, material swelling, high cost, and limited scalability. Here, we use a rapid prototyping approach incorporating patterned adhesive thin films to develop a reusable microfluidic device that can produce alginate hydrogel microbeads with high-throughput potential for microencapsulation applications. We show that beads formed in our device have high sphericity and monodispersity. We use the system to demonstrate effective cell encapsulation of mesenchymal stem cells and show that they can be maintained in culture for at least 28 days with no measurable reduction in viability. Our approach is highly scalable and will support diverse translational applications of microencapsulated cells.

Design of an Adhesive Film-Based Microfluidic Device for Alginate Hydrogel-Based Cell Encapsulation.

There is a significant interest in effective oral drug delivery of therapeutic substances. For probiotics, there is a particular need for a delivery platform that protects the bacteria from destruction by the acidic stomach while enabling targeted delivery to the intestine where microbiota naturally reside. The use of probiotics and how they impact the gut microbiota is a growing field and holds promise for the treatment of a variety of gastrointestinal diseases, including irritable bowel disease Crohn's disease and C. diff and other diseases, such as obesity, diabetes, Parkinson's, and Alzheimer's diseases.

Article	Year
Selective Osmotic Shock (SOS)-Based Islet Isolation for Microencapsulation. Methods in molecular biology (Clifton, N.J.)\| PubMed ID: 27738936	2017
Encapsulation of Mesenchymal Stem Cells in 3D Ovarian Cell Constructs Promotes Stable and Long-Term Hormone Secretion with Improved Physiological Outcomes in a Syngeneic Rat Model. Annals of biomedical engineering\| PubMed ID: 31367915	2020
Chemical Modification of Alginate for Controlled Oral Drug Delivery. Journal of agricultural and food chemistry\| PubMed ID: 31433940	2019
Design of an Adhesive Film-Based Microfluidic Device for Alginate Hydrogel-Based Cell Encapsulation. Annals of biomedical engineering\| PubMed ID: 31933001	2020
Development of a Novel Oral Delivery Vehicle for Probiotics. Current pharmaceutical design\| PubMed ID: 32039674	2020

Kevin Enck

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