Hydrogels and cell based therapies in spinal cord injury regeneration

Spinal cord injury (SCI) is a central nervous system- (CNS-) related disorder for which there is yet no successful treatment. Within the past several years, cell-based therapies have been explored for SCI repair, including the use of pluripotent human stem cells, and a number of adult-derived stem and mature cells such as mesenchymal stem cells, olfactory ensheathing cells, and Schwann cells. Although promising, cell transplantation is often overturned by the poor cell survival in the treatment of spinal cord injuries. Alternatively, the therapeutic role of different cells has been used in tissue engineering approaches by engrafting cells with biomaterials. The latter have the advantages of physically mimicking the CNS tissue, while promoting a more permissive environment for cell survival, growth, and differentiation. The roles of both cell- and biomaterial-based therapies as single therapeutic approaches for SCI repair will be discussed in this review. Moreover, as the multifactorial inhibitory environment of a SCI suggests that combinatorial approaches would be more effective, the importance of using biomaterials as cell carriers will be herein highlighted, as well as the recent advances and achievements of these promising tools for neural tissue regeneration.

Chitosan-based scaffolds for tissue regeneration: preparation and microstructure characterization

Scaffolds are porous three-dimensional supports, designed to mimic the extracellular environment and remain temporarily integrated into the host tissue while stimulating, at the molecular level, specific cellular responses to each type of body tissues. The major goal of the research work entertained herein was to study the microstructure of scaffolds made from chitosan (Ch), blends of chitosan and sodium alginate (Ch/NaAlg), blends of chitosan, sodium alginate and calcium chloride (Ch/NaAlg/CaCl2) and blends of chitosan, sodium alginate and hydroxyapatite (Ch/NaAlg/HA). Scaffolds possessing ideal physicochemical properties facilitate cell proliferation and greatly increase the rate of recovery of a damaged organ tissue. Using CT three-dimensional images of the scaffolds, it was observed that all scaffolds had a porosity in the range 64%-92%, a radius of maximum pore occurrence in the range 95m-260m and a permeability in the range 1×10-10-18×10-10 m2. From the results obtained, the scaffolds based on Ch, Ch/NaAlg and Ch/NaAlg/CaCl2 would be most appropriate both for the growth of osteoid and for bone tissue regeneration, while the scaffold made with a blend of Ch/NaAlg/HA, by possessing larger pores size, might be used as a support for fibrovascular tissue.

Development of advanced cell/tissue culture systems, based on enhanced polymeric scaffolds and sophisticated bioreactors, for tissue engineering applications

Programa Doutoral em Engenharia Biomédica

A 3D computer assisted Orthopedic Surgery Planning approach based on planar radiography

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Informática Médica)