The neuroprotective effect of rat adipose tissue-derived mesenchymal stem cell-conditioned medium on cortical neurons using an in vitro model of SCI inflammation

Objectives: In this study, anew approach was used with an in vitro model in which neural cells were exposed to conditioned media from the injured spinal cord (SCI-CM) mimicking a local inflammatory microenvironment . Subsequently, the neuroprotective effect of rat adipose tissue-derived msesenchymal stem cell-conditioned media (ATMSC-CM) was investigated through a cell-free based therapy, which was used to treat cortical neurons and astrocytes under inflammation. Methods: Primary cell cultures isolated from postnatal day (P6) Wistar rat brain cortex were exposed to SCI-CM derived from the central lesion, rostral and caudal segments of injured spinal cord. After 48h incubation, the SCI-CM was replaced and primary cultures were cultivated either in DMEM media alone or in ATMSC-CM for 72h. The impact of ATMSC-CM on the viability of neurons and astrocytes was assessed using a CyQUANT (R) Direct Cell Proliferation Assay Kit as well as immunocytochemistry analysis. Results: Immunocytochemical analysis revealed significant decrease in the number of MAP2 positive neurons exposed to SCI-CM compared to Control. Protection by ATMSC-CM was associated with increased survival of neurons compared to primary culture cultivated in DMEM media alone. The ATMSC-CM effect on astrocytes was more variable and without any significant impact. Conclusion: The results demonstrate that SCI-CM mimicking inflammation can reduce cortical neuron survival, and subsequent exposure to ATMSC-CM can stabilize the neuronal population most likely via released neuroprotective and trophic factors. In addition, astrogliosis was not affected by ATMSC-CM.