The effects of fused therapeutics combining transplantation of human mesenchymal stem cells and treatment of repetitive transcranial magnetic stimulation in Parkinsonian animal model

Abstract

Parkinson’s disease (PD) occurs as a result of cell death of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc). PD is characterized by certain motor disturbances such as resting tremor, bradykinesia, and gait disturbance. Repetitive transcranial magnetic stimulation (rTMS) has been used to treat neurological diseases such as stroke and PD. Although rTMS has been used clinically, the underlying mechanism still remains unclear. Transplantation of mesenchymal stem cells (MSCs) may help to recover the functional deficit of PD patients by replacing damaged dopaminergic neurons or through other beneficial mechanism. Combing rTMS treatment with transplantation of human mesenchymal stem cells (hMSCs), we made an attempt to establish a novel fused therapeutics for PD. This study was designed to provide a background for novel combined therapeutics for neurodegenerative diseases such as PD. For this purpose, neuroprotective effect for the nigral dopamine neurons, neurotrophic/ growth factors and anti-inflammatory cytokine regulation effect as well as functional recovery will be assessed in 6-OHDA-induced PD animal model after administration of hMSCs and rTMS. Adult Sprague–Dawley rats were unilaterally injected with 6-hydroxydopamine (6-OHDA) into two sites in the right striatum. rTMS was treated to rats with PD daily for 4 and 8 weeks. hMSCs were transplanted into the PD animal model via cisterna magna. Transplanted hMSCs were identified in the substantia nigra (SN), striatum (ST) and subventricular zone (SVZ). Survival rate of SN dopamine (DA) neurons and expression of tyrosine hydroxylase (TH) protein in rTMS treatment and/or hMSCs transplantation group was somewhat greater than that of untreated group. In particular, the highest survival rate and expression of TH protein was recorded in the rTMS+hMSCs group, indicating that combination treatment has a synergy effect for neuroprotection. The expression levels of brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), nerve growth factor (NGF) and platelet-derived growth factor (PDGF) were significantly elevated in the rTMS treatment and/or hMSCs transplantation group. Likewise, the highest growth factors expression was recorded in the rTMS+hMSCs group, indicating that rTMS+hMSCs treatment has a synergy effect. In addition, anti-/pro-inflammatory cytokine were significantly elevated (IL-10, IL-6)/ decreased (IFN-r, TNF-a) in the rTMS treatment and/or hMSCs transplantation groups. rTMS+hMSCs treatment has a synergy effect of cytokine expression. Assessment of treadmill locomotion test (TLT), somatosensory evoked potential (SEP) and amphetamine induced rotation test (AIRT). The TLT score was significantly improved in the rTMS treatment and/or hMSCs transplantation groups at 4, 6, 8 weeks post treatment/transplantation (wpt), it revealed that motor function was improved in PD rats. A synergy effect of rTMS+hMSCs for improvement of locomotor function was confirmed in TLT. Eight weeks after treatment, rTMS treatment and rTMS+hMSCs treatment group showed a significantly shortened latency, indicating that rTMS treatment and rTMS+hMSCs treatment/transplantation improved sensory-motor function. The rate of AIRT was significantly lowered in hMSCs group compared to that in the untreated rats at all the time point after treatment.Collectively our finding exhibit that rTMS treatment and/or hMSCs transplantation could induce a positive environment that is beneficial to cell survival within the rat brain with Parkinson through alteration of soluble factors such as neurotrophic/growth factors and anti-/pro- inflammatory cytokine relation with neuronal protection or repair. These results give PD rats preservation of DA neurons and improvement of motor functions. Furthermore, combining rTMS treatment and hMSCs transplantation has partially synergy effects. Therefore, present results may provide a novel techniques and a valuable theoretical background for development of therapeutics for patients suffered from Parkinson disease.