Traumatic spinal cord damage causes a permanent loss of motor and sensory functions in the central nervous system, termed
paraplegia or
tetraplegia based on the site of the injury. Other detrimental effects may take place in the
respiratory system and
renal system as a result of the injury. Unlike the peripheral nervous system, the central nervous system is unable to regenerate damaged axons, so its synaptic connections are lost forever. Current treatment is limited and the primary potential methods are either controversial or noneffective. Studies dating back to the 1990s have begun researching the olfactory system of mammals, rats in particular, to gain a greater understanding of axonal regeneration and
neurogenesis, and the possible implementation of these cells at the site of the spinal cord injury. Transplantation of OECs into the spinal cord has become a possible therapy for spinal cord damage and other neural diseases in animal models. Several recent studies have reported that preventing OEC inhibition will present a uniform population of cells in the spinal cord, creating an environment in which damaged axons can be repaired. In October 2014, the Polish firefighter
Darek Fidyka became the first paraplegic patient to regain mobility after OEC transplantation. OECs are similar to Schwann cells in that they provide an upregulation of low-affinity
NGF receptor p75 following injury; however, unlike Schwann cells they produce lower levels of
neurotrophins. Several studies have shown evidence of OECs being able to support regeneration of lesioned axons, but these results are often unable to be reproduced.
Peptide-modified gellan gum and OECs Stem cell transplantation has been identified as another possible therapy for axonal regeneration in the central nervous system by delivering these cells directly to the site of the spinal cord injury. Both OECs and neural stem/progenitor cells (NSPCs) have been successfully transplanted in the central nervous system of adult rats and have had either positive or neutral results as a method of neurogenesis and axonal regeneration; however, neither method has been shown to have long term beneficial effects, as cell survival is usually less than 1% after transplantation. Gellan gum hydrogel can be injected in a minimally
invasive manner and is approved by the FDA as a food additive because of its chemical structure. The gellan gum was modified with several
fibronectin-derived peptide sequences so the transplantation cells have closely related properties to that of native tissue in the
extracellular matrix. Transplantation of stem cells is also known to cause
toxicity and
graft-versus-host disease (GVHD).
Apoptotic cells have been administered simultaneously with hematopoietic stem cells in experimental transplantation models, in anticipation of an improved outcome. As a result, the combination prevents
alloimmunization, up-regulates
Regulatory T cells (suppressor T cells) and reduces the severity of GVHD. both of which have been identified as being susceptible to viral infection. == Labeling OECs ==