## 3 Results
### Effect of LTP on Cell Death and on the Proliferation and Growth of BMSC  
Mitochondrial degradation is known to be closely related to the induction of cell death [36]. We performed a microscopic study on the effect of LTP on the state of a BMSC culture near a needle electrode. One can see that within an hour after exposure of the cell culture to LTP, the cells on the border of the LTP-exposed zone (around 2 mm from the needle electrode) displayed morphological changes specific for the development of apoptosis (e.g., cell shrinkage and fragmentation associated with the formation of apoptotic bodies with compacted chromatin (Figure 4B)). No changes in the morphology of cells located farther from the needle electrode were observed (data not shown). Figure 3: Time-dependent changes in mitochondrial potential, biogenesis and dynamics in the BMSC in response to LTP treatment (blue bars). Panels A and B show the effect of LTP on (**A**) the mitochondrial potential of BMSC, assessed by rhodamine-123 (Rh-123) fluorescence, and (**B**) the ratio of mtDNA to nDNA. A real-time quantitative polymerase chain reaction (qPCR) was carried out to determine the mtDNA copy numbers as a mitochondrial (ND1) to nuclear (globulin) ratio. Panels C–J show the effect of LTP on the relative expression (to \(\beta\)-actin (bAct) of the following genes: (**C**) PGC-1a; (**D**) DRP1; (**E**) OPA1; (**F**) MFN1; (**G**) MFN2; (**H**) PINK1; (**I**) Parkin; and (**J**) FIS1. Panels (**L,K**) show the effect of hydrogen peroxide (50 and 100 \(\upmu\)M, respectively) on the mitochondrial potential of the BMSC in the absence of LTP treatment (grey bars). The green bars indicate no exposure to plasma. The values are given as means \(\pm\) SEM (\(n=3\)). \({}^{*}\)\(p<0.05\) compared to the control. A comprehensive cell culture micrograph is presented below (Figure 5). The micrograph was obtained by overlaying three images obtained in different fluorescence channels. The nuclei of all the cells before plasma treatment are colored blue on the micrograph (Hoechst 33342, Figure 5A). After plasma treatment, the vast majority of the cells acquired pink-colored nuclei of varying intensities (propidium iodide), indicating that these cells were damaged and were in different stages of apoptosis (Figure 5B). We also evaluated the expression level of a gene of one of the key enzymes activated during apoptosis, effector caspase 3, as well as a gene of c-Jun-N-terminal protein kinase (JNK) involved in the initiation of apoptosis, including in response to the development of oxidative stress [34]. As can be seen from Figure 6, the level of gene expression of these apoptosis factors in stem cells increased  
Figure 4: Micrographs of a BMSC culture 1 (**A**,**B**), 24 (**C**) and 36 (**D**) hours after exposure to LTP. Microphotographs were taken at the location of the needle electrode, on which the plasma formation process took place. The scale bars were 500 \(\upmu\)M (**A**,**C**,**D**) and 40 \(\upmu\)M (**B**). Black arrows indicate vesiculation of the cytoplasmic membrane. Figure 5: Micrographs of the BMSC culture before plasma treatment (**A**) and 24 h after exposure to LTP (**B**), obtained by an overlay of three fluorescent channels and transmitted light. Cytoplasm is colored green, viable cell nuclei are colored blue (Hoechst 33342) and a pink color (propidium iodide) indicates apoptotic cell nuclei. The scale bars are 20 \(\upmu\)M.  
significantly during the first two days after exposure to LTP and showed a tendency to decrease on the third day. It is known that ROS, along with the induction of destructive processes, can also stimulate regenerative processes in the tissues of living organisms [20; 21; 22]. One of the mechanisms of inducing cell proliferation is the participation of ROS in the activation of mitogenic signaling pathways [34].