Cell-based clinical therapies for spinal cord injury treatment

• Autor(a) principal: Cruz, Bruna Daniela Coelho da
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/33616
• topic: Spinal cord lesion; Cell therapy; Clinical trials; Safety and efficacy; In vitro PBMCs culture

Spinal cord injury (SCI) is an untreatable neuropathology that causes severe disfunction and disability. Cell-based therapies hold neuroregenerative and neuroprotective potential and, although studied in SCI patients for more than two decades, long-term efficacy and safety remain unproven, and it is still debated which cell types result in higher functional recovery. This thesis comprises a comprehensive review of 100 SCI cell-based clinical trials, discussing its trends and critically analyzing their strengths and limitations. The type of cells used - olfactory ensheating cells (OECs), Schwann cells, macrophages, neural stem cells (NSCs) and other stem cells (SCs) derived from various tissues, including peripheral blood (PB) - were compared in terms of effectiveness, by using gold-standard efficacy outcome measures like the ASIA Impairment Scale (AIS). Most of the trials are in early phases of clinical development, involve patients with traumatic, chronic and complete injuries, and do not display a randomized comparative control arm. Bone marrow (BM-)SCs and OECs are the most used cells, and open surgery and injection the most common delivery methods. Amon the SCs, autologous PB-SCs transplants showed the highest percentage of patients with AIS improvement, while NSCs allotransplants (from human embryos/foetus) yielded the highest percentage of AIS improvement by 2 or more grades. Therefore, these cells may hold a promising potential for SCI cell therapy, but a standardization of the trials is needed to allow unbiased comparisons and draw more relevant conclusions. PB-SCs for autologous transplants are isolated within peripheral blood mononucleated cells (PBMCs). Further, NSC derived from induced-pluripotent stem cells (iPSCs), arising from reprogrammed PBMCs, could comprehend a safer and more easily-obtained NSC-based therapy. A pilot study was thus conducted on good practices for in vitro PBMCs culture, with the goal of implementing it in our lab and aiming to further explore them as a source of cells for SCI therapy. Blood samples from 3 healthy donors were used to optimize PBMCs’ isolation, expansion, and cryopreservation. A mean of 1.69x106 PBMCs could be isolated per mL of collected blood. When cultured in vitro for 7 days, PBMCs tend to decline in number but their metabolic activity increases in last days of culture. Hematopoietic SCs (CD45+/CD34+), a potential source for iPSCs, were slightly enriched. The best cryopreservation method was the one using 70% FBS. Overall, the implementation of PBMCs’ culture techniques was successful, but further studies with a bigger sample size need to be carried out to confirm these results.