Fig. 1

Schematic diagram of cell transplantation treatment. With the potentials of exerting multiple functions, the transplanted cells enter the brain, migrate to the injured site, and transform into neuron-like cells, directly replacing damaged/necrotic neurons surrounding non-injured nerves. Knowledge on stem cell mechanisms based on neuroprotective effects is summarized but still limited. Additionally, MSC have a strong paracrine effect, secreting or promoting BDNF, GDNF, VEGF, and other active substances [42]. The retained cells are expected to promote the survival, proliferation, and differentiation of new progenitors, promote the formation of new blood vessels, migrate to the injury site, and help to engage the neural circuit by promoting the formation of synapses