Human islet mass, morphology, and survival after cryopreservation using the Edmonton protocol

Abstract

The aim of this study was to assess recovery, cell death, and cell composition of post-thaw cultured human islets. Cryopreserved islets were provided by the Clinical Islet Transplant Program, Edmonton, Canada. Islets were processed using media prepared in accordance with Pre-Edmonton and Edmonton protocols. Cryopreserved islets were rapidly thawed and cultured for 24 h, 3 d, 5 d, and 7 d, following which they were processed for histology. Islet quantification, integrity, morphology and tissue turnover were studied via hematoxylin and eosin stained sections. Ultrastructure was studied by electron microscopy and endocrine cell composition by immunohistochemistry. Using the Pre-Edmonton protocol, islet recovery was 50.1% and islet survival was 50% at 24 h while for the Edmonton protocol, the islet recovery was 69.4% (p<0.001) and islet survival, 50% at ≈2.5 d. With an increasing culture duration although the physical integrity was retained there was an increasing loss of cohesivity both at light microscopic and at ultrastructure level regardless of the protocols used. Percentage islet survival and tissue turnover correlated negatively with culture duration in both protocols. The Edmonton protocol appears to preserve the islets better. However, culture duration adversely affects islet survival and quality, indicating the need for more optimal cryopreservation and culture techniques.

Current Advancements in Pancreatic Islet Cryopreservation Techniques

“…The Edmonton method of islet isolation was shown to improve islet survival during islet cryopreservation as well. A study comparing cryopreserved islets before the establishment of the Edmonton protocol to human islets treated via Edmonton method observed a 24-hour survival rate increase of 19.3% (50.1 versus 69.4% respectively) with added increases recorded after 7 days of culture [8]. Although the impact of the Edmonton protocol on cryopreservation is significant, there is still vast room for improvement in the islet cryopreservation process.…”

Effects of cryopreservation on adipose tissue‐derived microvascular fragments

“…If required in a later stage of life, the stored ad‐MVF could be retransferred into tissue defects of these patients. However, although successful cryopreservation and transplantation of different tissues, such as parathyroid glands (Guerrero, ), pancreatic islets (Miranda et al, ), and ovarian tissue (Andersen, Kristensen, Greve, & Schmidt, ), is clinically well established, nothing is known so far about the influence of the freeze‐thaw procedure on the vascularization potential of isolated ad‐MVF.…”

Sensing and Sensibility: Single‐Islet‐based Quality Control Assay of Cryopreserved Pancreatic Islets with Functionalized Hydrogel Microcapsules

“…[ 15,28,29 ] Ongoing challenges in islet encapsulation include biocompatibility of the capsule material, islet injury, and function loss during encapsulation process, mechanical and chemical stability of the capsule membrane, repeatability, reproducibility, and the optimal permeability of capsule membranes. [16][17][18] In addition, if cryopreservation is applied, islets inside the capsule should survive the freezing and thawing procedures with minor or no major structural modifi cations of the capsule membrane, to maintain the permeability, pore size, morphology, surface roughness, and rigidity of the membrane.…”

“…Each human islet isolation procedure costs about $20 000 in the USA. [ 18 ] Long-term storage of the donor tissue by cryopreservation provides an effective solution. [ 19 ] A bank of cryopreserved islets with diverse HLA (human leukocyte antigen) phenotypes enables the optimization of screening and matching between donors and recipients, provides quality control monitoring and microbiological sterility of the islets, and allows time to induce the immune unresponsiveness in the recipient.…”