A triple-transgenic (tyrosine hydroxylase/dopamine decarboxylase/GTP cyclohydrolase 1, TH/DDC/GCH1) bone marrow mesenchymal stem cell line (BMSCs) capable of stably synthesizing dopamine (DA) transmitters were established to provide experimental evidence for the clinical treatment of Parkinson\'s disease (PD) by using this cell line. The DA-BMSCs cell line that could stably synthesize and secrete DA transmitters was established by using the triple transgenic recombinant lentivirus. The triple transgenes (TH/DDC/GCH1) expression in DA-BMSCs was detected using reverse transcription-polymerase chain reaction (RT-PCR), Western blotting, and immunofluorescence. Moreover, the secretion of DA was tested by enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). Chromosome G-banding analysis was used to detect the genetic stability of DA-BMSCs. Subsequently, the DA-BMSCs were stereotactically transplanted into the right medial forebrain bundle (MFB) of Parkinson\'s rat models to detect their survival and differentiation in the intracerebral microenvironment of PD rats. Apomorphine (APO)-induced rotation test was used to detect the improvement of motor dysfunction in PD rat models with cell transplantation. The TH, DDC and GCH1 were expressed stably and efficiently in the DA-BMSCs cell line, but not expressed in the normal rat BMSCs. The concentration of DA in the cell culture supernatant of the triple transgenic group (DA-BMSCs) and the LV-TH group was extremely significantly higher than that of the standard BMSCs control group (P < 0.000 1). After passage, DA-BMSCs stably produced DA. Karyotype G-banding analysis showed that the vast majority of DA-BMSCs maintained normal diploid karyotypes (94.5%). Moreover, after 4 weeks of transplantation into the brain of PD rats, DA-BMSCs significantly improved the movement disorder of PD rat models, survived in a large amount in the brain microenvironment, differentiated into TH-positive and GFAP-positive cells, and upregulated the DA level in the injured area of the brain. The triple-transgenic DA-BMSCs cell line that stably produced DA, survived in large numbers, and differentiated in the rat brain was successfully established, laying a foundation for the treatment of PD using engineered culture and transplantation of DA-BMSCs.

Object Exclusively dopamine-producing pheochromocytoma/paraganglioma (PPGL) is an extremely rare subtype. In this condition, intratumoral dopamine β-hydroxylase (DBH), which controls the conversion of norepinephrine from dopamine, is impaired, resulting in suppressed norepinephrine and epinephrine production. However, the rarity of this type of PPGL hampers the understanding of its pathophysiology. We therefore conducted genetic and immunohistological analyses of a patient with an exclusively dopamine-producing paraganglioma. Methods Paraganglioma samples from a 52-year-old woman who presented with a 29.6- and 41.5-fold increase in plasma and 24-h urinary dopamine, respectively, but only a minor elevation in the plasma norepinephrine level was subjected to immunohistological and gene expression analyses of catecholamine synthases. Three tumors carrying known somatic PPGL-related gene variants (HRAS, EPAS1) were used as controls. Whole-exome sequencing (WES) was also performed using the patient\'s blood and tumor tissue. Results Surprisingly, the protein expression of DBH was not suppressed, and its mRNA expression was clearly higher in the patient than in the controls. Furthermore, dopa decarboxylase (DDC), which governs the conversion of 3,4-dihydroxyphenyl-L-alanine (L-DOPA) to dopamine, was downregulated at the protein and gene levels. In addition, melanin, which is synthesized by L-DOPA, accumulated in the tumor. WES revealed no PPGL-associated pathogenic germline variants, but a missense somatic variant (c.1798G>T) in CSDE1 was identified. Conclusion Although pre-operative plasma L-DOPA was not measured, our histological and gene expression analyses suggest that L-DOPA, rather than dopamine, might have been overproduced in the tumor. This raises the possibility of pathophysiological heterogeneity in exclusively dopamine-producing PPGL.