ABSTRACT
BACKGROUND: Currently, it was confirmed that encapsulating islets with natural or synthetic biomaterials to form a barrier with the function of immune isolation can not only reduce the systematic use of immunosuppressive agents to a certain extent, but also make heterogenous islet transplantation possible. OBJECTIVE: To introduce the research progress of the biomaterials for islet transplantation, describe several models for encapsulating islet, and eventually discuss current research focus and prospects of islets encapsulating models. METHODS: The authors searched PubMed and Web of Science databases with the search terms “islet encapsulation, islet transplantation biomaterials, islet transplantation hydrogel” for relevant papers published. Initially, a total of 447 papers were retrieved, and 89 of them were included in the final analysis. RESULTS AND CONCLUSION: There are two main deficiencies in islet encapsulation for transplantation: one is the attack of immune rejection by the recipient; the other is the shortage of supply of oxygen and nutrient. Encapsulation of islet with a single material, synthetic or natural biomaterial, cannot address the two issues mentioned above. Herein, the biomaterial used for islet encapsulation must be modified. Current islet hydrogel models tend to combine synthetic biomaterials with natural biomaterials to take full advantage of the two kinds of biomaterials. In addition, immune-regulating drugs, angiogenic factors, or factors promoting the survival or function of islets can also be incorporated into the biomaterial. Besides, other cells can be involved to co-transplant with islets in the hydrogel. How to incorporate various strategies for addressing the above issues properly is the key of future research.
ABSTRACT
Helminth infection can lead to organic,digestive and other tissue's pathological damage.Helminth diseases are harmful to human and animal health,and can cause reproductive failure,inhibits the growth and development of juvenile ani-mals,even lead to death of humans and animals in serious cases,and poses significant impacts on public health and causes eco-nomic losses to the animal husbandry.Currently,the prevention and control of helminth disease is largely dependent on inte-grated control measures including the use of drugs.Due to drug residues,drug resistance,and other issues,the development of new drugs and vaccines is imminent.So far,there is few ideal vaccines to control helminth diseases,which is due to that hel-minths have evolved mechanisms to evade host immune attacks during evolution,such as immune isolation,antigen variation, molecular simulation and so on.Therefore,this review describes the recent research advances in the immune evasion strategies of parasitic helminth,which aims to provide a reference for the development of new vaccines or drugs for better prevention and control of helminth diseases.
ABSTRACT
Cell microencapsulation aims to wrap the living target cells by one or several materials with good biological compatibility and semipermeable membrane properties.Cell microencapsulation not only can achieve immune isolation and prevent the attacks by macromolecular immunes and immune cells,but also can allow the free access of metabolites,small molecule nutrients and bioactive substances to the microcapsule.With the continuous progress of interdisciplinary technologies,cell microencapsulation shows increasing application prospects of making up a variety of limitations of organ transplantation.Moreover,with the development and maturation of cell microencapsulation,it has shown a strong advantage in regenerative medicine,which will certainly promote the rapid development of artificial cells and artificial organs.In this paper,the preparation of cell microcapsules,the effects of the outer membrane of microcapsules on immunological macromolecules and cytokines,the immunogenicity of the outer membrane,and the representative applications of cell microencapsulation were summarized.
ABSTRACT
Cell microencapsulation aims to wrap the living target cells by one or several materials with good biological compatibility and semipermeable membrane properties.Cell microencapsulation not only can achieve immune isolation and prevent the attacks by macromolecular immunes and immune cells,but also can allow the free access of metabolites,small molecule nutrients and bioactive substances to the microcapsule.With the continuous progress of interdisciplinary technologies,cell microencapsulation shows increasing application prospects of making up a variety of limitations of organ transplantation.Moreover,with the development and maturation of cell microencapsulation,it has shown a strong advantage in regenerative medicine,which will certainly promote the rapid development of artificial cells and artificial organs.In this paper,the preparation of cell microcapsules,the effects of the outer membrane of microcapsules on immunological macromolecules and cytokines,the immunogenicity of the outer membrane,and the representative applications of cell microencapsulation were summarized.
ABSTRACT
Objective To develop a new method of immune isolation for transplanting pig islets to rat to observe the effects on diabetic rats.Method Diabetes of rat was induced by streptozotocin.Pancreas of pig was digested with type V collagenase.The pig islets were purified by density gradient centrifugation.Insulin stimulation index of the purified pig islets was evaluated.Liver of the 18 diabetic rats and 6 normal rats was exposed by operation.Capsule at one edge of the liver lobe was cut apart and separated from liver parenchyma on both sides of the lobe.An artificial cyst was constructed by a cellulose ester (CE) dialysis bag with a ball of hollow fibers in the bag,and each end of the bag was closed by a thread.Each end of the bag was stuffed into the subcapsule of each side of the liver lobe.The thread at each end of the bag was passed through a hole of the capsule at other edge of the lobe and linked to each other around the lobe to hold the artificial cyst on the liver parenchyma.Middle part of the cyst (with the ball of hollow fibers in) was put between the cuts of capsule and under the skin.The collagen solution (pH 7.4) with pig islets (4000 IEQ) was injected into the subcapsule artificial cyst of 12 diabetic rats as experiment group.The collagen solution without pig islets was injected into the subcapsule artificial cyst of 6 diabetic rats and 6 normal rats as diabetes control group and normal control group respectively.The cut was sutured.The collagen solution became a collagen gel in the artificial cysts.At 8th week of the initial transplantation,the solution with pig islets (2000 IEQ) was injected percutaneously again into the subcapsule artificial cyst of each rat of the experiment group.Rats of the three groups were raised as usual,and the levels of fasting blood glucose were measured regularly.Result The insulin stimulation index of the purified pig islets was 2.2 ± 0.2.At 1st to 8th week of the initial transplantation,the levels of fasting blood glucose in the experiment group at every time point were lower significantly than those in the diabetes control group (P＜0.01).At 13th week of the initial transplantation,there was no significant fibroplasia around the subcasule artificial cysts in the rats by visual observation.Conclusion CE dialysis bag in the liver capsule at 13th week did not show significant stimulation to the surrounding tissues.Pig islets isolated in the subcapsule artificial cyst of rats might live normally and perform hypoglycemic action.Pig islets could be percutaneously injected into the subcapsule artificial cyst.
ABSTRACT
Objective To determine the effect of diffusion chamber for immune isolation and the proliferation of allogenic hybridoma within diffusion chamber in mice. Methods The hybridoma cell strain was established from SP2/0 cells and the splenocytes of BALB/c mouse by PEG mediate technique. The cells were injected peritoneally into BALB/c ( n =5) and C57 BL/6 (B6, n =5) mice. Diffusion chambers with microporous membrane containing hybridoma cells were implanted peritoneally into 5 BALB/c and 5 B6 mice. Results Within two months after peritoneal injection of the cell strain, four BALB/c mice developed bloody ascites and one developed abdominal tumor, but the B6 mice developed neither ascites nor tumor. After 30 and 101 days of the chamber implantation, the chambers were coated by omentum or mesenterium in all the animals of both strain groups and freshly formed blood vessels to the chamber membrane could be observed. Within the chambers, tumor developed, but the tumor could not fully fill the inner space of the chamber during the whole observation period. Conclusion The hybridoma cells established from SP2/0 cells and the splenocytes of BALB/c mouse may carry BALB/c MHC antigen. The diffusion chambers can effectively isolate immune rejection. Freshly formed blood vessels to the chamber membrane can support the cells within the chambers.