Novel strategy to produce a drug delivery system for skin regeneration

• Autor(a) principal: Gaspar, Diana Patrícia Rodrigues
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/1118
• topic: Pele - Lesões - Regeneração; Alginato; Encapsulamento de células; Micropartículas; Nanopartículas; Quitosano

Skin lesions are traumatic events that lead to the increase of fluid loss, infections, scarring and locally immunocompromised regions. These injuries can be caused by genetic disorders, acute trauma or even surgical interventions. In these situations, a substantial area of skin can be damaged, often without the possibility of being regenerated. Scientists have put a lot of effort in the development of suitable drug delivery systems suitable to release therapeutic molecules that are required for the initials phases of the wound healing process. Cell microencapsulation arises as an alternative approach for sustained in situ cell delivery. This technology is based on the immobilization of cells within a polymeric matrix, surrounded by a semi-permeable membrane, that isolate the encapsulated cells from the host immune system. Nonstanding, the microparticulate matrix still allows the exchange of nutrients, gases, waste and releasing of bioactive molecules, such as extracellular matrix components and growth factors secreted by cells. Nevertheless, the optimization of cell-based therapy demands the development of alternative strategies to improve cell administration. Alginate has been used for cell microencapsulation, due to its simple gelling process, excellent biocompatibility, biodegradability properties and its stability under in vivo conditions. On the other hand, nanoparticulate systems have been widely used in the biomedical field, as drug delivery devices that can improve the efficiency and widening the applications of the microencapsulation systems. Therefore, the present study aimed to develop biodegradable alginate microparticles that were used for human fibroblasts cells and chitosan nanoparticles encapsulation, in order to improve the wound healing process. To do so, two types of microparticles were firstly produced with alginate and a mixture of alginate and collagen. Subsequently, these carriers were characterized according to their size and geometry by scanning electron microscopy. Confocal images were also acquired to confirm cell encapsulation in microparticles. The cytotoxic profile of the carriers was assessed. Cell release from microparticles was observed over time after encapsulation through optical microscopic analysis. In second part of the work, chitosan nanoparticles loaded with a model protein (bovine serum albumin) were produced and were incorporated in microparticles. The encapsulation efficiency of this protein in nanoparticles was determined. Then, both the morphology and size of these nanoparticles were characterized. The results herein obtained showed that the developed microparticles and nanoparticles can be used as systems tailored for sustainable cells and drug release.