A new method for encapsulation of living cells: preliminary results with PC12 cell line.
ABSTRACT A new method is described for encapsulation of living cells. PC12 rat adrenal pheochromocytoma cells, which have been shown to synthesize, store and release dopamine were employed. The particles are made first and the cells then incorporated in a gentle mechanical procedure. The morphology (by light and electron microscopic observation), stability, rheology, texture and permeability of these microcapsules provided by Kappa Biotech were investigated. Membrane permeability studies demonstrated exclusion of 69,000 Da human serum albumin, but equilibrium of D-glucose and inulin was within 24h, indicating a molecular weight cut-off in the 5000-70,000 Da range. The viability and the function of the encapsulated cells were evaluated by measuring the spontaneous release of dopamine by high performance liquid chromatography with electrochemical detection. The results show that dopamine-secreting cells can be sequestered in a semi-permeable capsule and still display good viability and proliferation for at least 1 month.
SourceAvailable from: Xavier Banquy[Show abstract] [Hide abstract]
ABSTRACT: Cell encapsulation in microcapsules allows the in situ delivery of secreted proteins to treat different pathological conditions. Spherical microcapsules offer optimal surface-to-volume ratio for protein and nutrient diffusion, and thus, cell viability. This technology permits cell survival along with protein secretion activity upon appropriate host stimuli without the deleterious effects of immunosuppressant drugs. Microcapsules can be classified in 3 categories: matrix-core/shell microcapsules, liquid-core/shell microcapsules, and cells-core/shell microcapsules (or conformal coating). Many preparation techniques using natural or synthetic polymers as well as inorganic compounds have been reported. Matrix-core/shell microcapsules in which cells are hydrogel-embedded, exemplified by alginates capsule, is by far the most studied method. Numerous refinement of the technique have been proposed over the years such as better material characterization and purification, improvements in microbead generation methods, and new microbeads coating techniques. Other approaches, based on liquid-core capsules showed improved protein production and increased cell survival. But aside those more traditional techniques, new techniques are emerging in response to shortcomings of existing methods. More recently, direct cell aggregate coating have been proposed to minimize membrane thickness and implants size. Microcapsule performances are largely dictated by the physicochemical properties of the materials and the preparation techniques employed. Despite numerous promising pre-clinical results, at the present time each methods proposed need further improvements before reaching the clinical phase.Biotechnology Progress 07/2009; 25(4):946-63. DOI:10.1002/btpr.226 · 1.88 Impact Factor
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ABSTRACT: Adrenal medullary chromaffin cells synthetize and secrete a combination of pain-reducing neuroactive compounds including catecholamines and opioid peptides. Previous reports have shown that implantation of chromaffin cells into the spinal subarachnoid space can reduce both acute and chronic pain in several animal models. We recently demonstrated that human chromaffin cell grafts in the cerebrospinal fluid (CSF) could alleviate intractable cancer pain after failure of systemic opiates. However, wider application of this approach was limited by the limited availability of allogeneic donor material. Alternatively, chromaffin cells from xenogeneic sources such as bovine adrenal medulla were successful in the experimental treatment of pain, but recent concern over risk of prion transmission precluded use of bovine grafts in human clinical trials. The objective of the present study was to investigate the possibility of developing a new xenogeneic porcine source of therapeutic chromaffin cells because this strategy is currently considered the safest for transplantation in man. In the present study, we report the isolation and the characterization of primary porcine chromaffin cells (PCC) compared to bovine cells. We show, for the first time, that these cells grafted in the rat subarachnoid space can attenuate pain-related behaviors as assessed by the formalin test, a model of tonic pain. Moreover, in addition to behavioral studies, immunohistochemical analysis revealed robust survival of chromaffin cells 35 days after transplantation. Taken together, these results support the concept that porcine chromaffin cells may offer an alternative xenogeneic cell source for transplants delivering pain-reducing neuroactive substances.Experimental Neurology 05/2004; 186(2):198-211. DOI:10.1016/j.expneurol.2003.10.018 · 4.62 Impact Factor
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ABSTRACT: Implantation of encapsulated cells in particles of less than 1 mm (micro-encapsulation) has been proposed as a cell synthesized bio-molecule delivery system. Encapsulation provides immuno-isolation, protecting foreign cells from host immune system while nutrients, oxygen and therapeutic products can diffuse freely across capsule walls. A new method is described for the synthesis of a new family of hollow microparticles for cell encapsulation. Unlike other micro-encapsulation methods, encapsulation in those devices will take place after capsule synthesis, by micro-injection. The microcapsules were prepared by a three-steps original procedure: first, synthesis of a core particle, followed by coating with a layer of epichlorohydrin cross-linked amylo-pectin gel and, finally, selective degradation of the core particle to create the cavity. Initial experiments make use of amylo-pectin cross-linked with trimetaphosphate as core particle material. However, selective degradation was difficult to achieve. In further essays, polyesters were used successfully for the preparation of core particles. Optimizations were carried out and the permeability and morphology of the hollow particles were investigated. The preliminary results show that the new method has the potential to become a standard procedure to obtain hydrogel hollow particles. Moreover, the permeability study seems to be in accordance with specifications for immuno-isolation.Journal of Microencapsulation 06/2004; 21(4):413-31. DOI:10.1080/02652040410001729223 · 1.88 Impact Factor