Microencapsulating human cells

Uludag H, Hwang JR, Sefton MV. Microencapsulated human hepatoma (HEPG2) cells— capsule-to-capsule variations in protein secretion and permeability. J Controlled Release 1995 33 273-283. 

Potential problems for the use of the xenogeneic stromal cells in a clinical setting may include transfer of infectious diseases or rejection of transplanted HSCs. Therefore, a human bone marrow (hBM) stromal cell line has been developed, which demonstrated potential support for multilineage differentiation (Bertolini et al. 1997). Furthermore, microencapsulated feeder cells have been investigated and demonstrated effective expansion of human UCB (hUCB) cells (Fujimoto et al. 2007). 

Human Burkitt Lymphoma ( Raji ) cells were obtained frozen from the American Type Culture Collection thawed, and cultured, in RPMI containing 10% Fetal Bovine Serum. The polymers for microencapsulation were dissolved in distilled water with pH adjustment to 7.4, and dialysed extensively against distilled water through a 104 Da cut off dialysis bag. The polymers were then pH adjusted to 7.4 and freeze dried to constant weight. Final preparation for the microencapsulation process was limited to dissolution in appropriate medium and filtration through a 0.4 pm cartridge. 

Probiotics have been considered bioactive living cells, that is, microorganisms that can confer human health benefits and well-being when they are consumed alive and frequently. However, these microorganisms are very sensitive to many factors, because of that, they are inherently unstable. Therefore, microencapsulation has been used as an alternative to protect these microorganisms and to release them in their site of action (Favaro-Trindade et al., 2011). 

In plant cell cultures, microencapsulation, by mimicking cell natural environment, improves efficiency in production of different metabolites used for medical, pharmacoIogicaL and cosmetic purposes. Human tissues are turned into bioartiflcial organs by encapsulation in natural polymers and transplanted to control hormone-deficient diseases such as diabetes and severe cases of hepatic failure. In continuous fermentation processes, immobilization is used to increase cell density, productivity and to avoid washout of the biological catalysts from the reactor. This has already been applied in ethanol and solvent production, sugar conversion, or wastewater treatment. 

In diabetes (where there is poor insulin delivery by the pancreas in response to glucose) or Parkinson s disease (where there is poor release of dopamine in response to potassium), it has been recommended to transplant encapsulated animal cells in the human body to supplement the existing deficiency. The limitation of this cell transplant is the immune-mediated rejection, and to overcome this, the cells are microencapsulated with acrylates and methacrylates, which carmot be penetrated by large antibodies but insulin or dopamine can diffuse out easily. Readily available methacrylates [CH2=C(CH3)—C(0)0R] are MAA (methacrylic acid with R as H), MMA (methyl methacrylate with R as CH3), HEMA (2-hydro-xyethyl methacrylate with R as —CH2CH2OH), HPMA (2-hydroxy methyl methacrylate with R as —CH2CH(OH)—CH3), and DMAEMA [dimethyl-... 

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