Multiple stimulations of chemoluminescent-expressing mesenchymal-derived dopaminergic transplants safely reinforce limb-use control restoration during swimming in a unilateral Parkinson's disease model.

In Parkinson's disease (PD), dopaminergic (DA) neurons deteriorate within the substantia nigra pars compacta (SNc), causing movement difficulties. This deterioration can be modeled in rats given large, unilateral DA-depleting lesions of the nigrostriatal pathway using the neurotoxin 6-hydroxydopamine. The behavioral benefits promoted by classic L-DOPA pharmacotherapy typically do not include skilled limb use restoration. Among deteriorative diseases, the single neurotransmitter loss in PD allows for a more discrete or focused replacement goal. Stem cell therapy (SCT) would be more likely to help restore skilled limb use if it integrates successfully into the host. We surmise that more stable or persistent PD SCT will require active guidance or context signaling while connecting within a hospitable host environment to integrate successfully and ensure behavior-responsive host control. To explore this, we examined the supportive effects of swimming exercise alone or exercise with transplantation of modified LMO3-containing mesenchymal stem cell (MSC)-derived dopaminergic transplants, and, in both cases with or without varying degrees of swim-correlated direct chemogenic activated optogenetic stimulation of the transplanted cells. We were interested in whether increasing selective and behavior-correlated transplant stimulation more than once during early integration might guide reconstructive events and enhance behavioral improvement following DA loss without producing undesirable repercussions. Our study evaluated forelimb cooperative control in rats using a recorded swimming task to assess exercise/transplant/stimulation-related improvements. Combined transplant stimulation and swimming facilitated transplant-derived forelimb cooperation during swimming after a single exposure. Two distinct stimulations supported this recovery both safely, and more effectively, than just one.