Clinical neural scaffold engineering for olfactory ensheathing cells.
Doctoral thesis, UCL (University College London).
Transplantation of olfactory ensheathing cells (OEC) is one of the most promising current approaches to repair spinal cord injury. The encouraging results from transplantation of OECs in animal models have led to several clinical applications of these cells in spinal cord injury. The first controlled clinical trial was carried out by Mackay-Sim, Féron and colleagues (Mackay-Sim et al., 2008). A number of neurosurgical teams have also implanted foetal OECs (Huang et al., 2003) or minced whole mucosal tissue (Lima et al., 2006) into spinal injuries. So far the reported functional benefits are only moderate. The Mackay-Sim team reported no improvements while others reported minor improvements (including an ongoing trial by Pawel Tabakow’s team in Poland; personal communication). The basic conclusion is that OEC transplantation is feasible and safe. However, in the studies where suspensions of OECs were used there were not enough cells to fill the lesion, and no materials were used to bridge the gaps. In order to progress to more effective transplants the two areas addressed in this thesis will be important – what is the best source of adequate numbers of cells, and what biomaterials can be used to bridge the gaps. In addressing the twin necessities of (a) identifying the tissue source needed to provide sufficient cells for transplantation and (b) the problem of bridging the large gaps present in spinal cord injuries, the results of this study were directed towards two issues. (a) The questions of cell source and proliferation were addressed by establishing the quantitative baseline for the yield of primary cultures from the olfactory bulb, and the whole and split olfactory mucosa and characterising the heterogeneity of these cultures in search for any difference between bulbar and mucosal OECs. The study of flow cytometric simultaneous antigenic bivariate cell cycle of purified OECs and ONFs from these four sources revealed the evolution of population heterogeneity and its strikingly differences between these four sources of primary tissue with additional populations that were not previously described. An unexpected highly proliferative p75+ population in the stripped mucosal epithelium was also characterised. Correlation study of the cell proliferation and population evolution revealed cell autonomous among the difference sources. (b) The feasibility of a synthesis biomaterial for the deployment of OECs and olfactory nerve fibroblasts (ONFs) as a transplant was addressed by designing and developing an electrospun PLGA nanocomposite nanofibre construct with a myriad of microfabrication techniques, focusing on how OECs and ONFs can be deployed during tissue culture and transplantation. The techniques included nanocomposite electrospinning, replica moulding from photolithographed silicon mould, design of tissue-culture membrane insert, and laser ablation. The biocompatibility study showed that when grown on a fibre mesh structured at the nano-scale, OECs responded by adopting the elongated form comparable to that which occurs when the convey regenerating fibres cross small lesions in in vivo transplants. Preliminary functional studies of using the nanocomposite nanofibers as a neural scaffold in the organotypic entorhino-hippocampus slice co-culture data provide an indication that the nanofibres are compatible with tissue and allow migration of astrocytes and growth of nerve fibres. These observations will be important in future attempts to derive larger cell populations for transplantation. The anticipated use of the OEC nanofibre prosthesis would be in the application of autologous human OECs for bridging the gap in spinal cord lesions.
|Title:||Clinical neural scaffold engineering for olfactory ensheathing cells|
|Open access status:||An open access version is available from UCL Discovery|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Neurology|
Archive Staff Only