Based on the 2020 census data, it is estimated that more than 7.5 million people aged 20 or older suffer from psoriasis in the USA. Psoriasis remains one of the most common and intractable immune-mediated diseases experienced by many adults worldwide. The most common type of psoriasis is plaque psoriasis. It manifests as red and whitish scaly patches affecting various body areas and is associated with serious health conditions, e.g. diabetes, cardiovascular disease, lymphoma, and depression.A 19 y/o male presented with a 5-year history of severe plaque psoriasis accompanied by depression and suicidal thoughts. He had received systemic treatments including methotrexate, acitretin, cyclosporine, etanercept, and psoralen plus ultraviolet A (PUVA) without effectiveness.A biopsy of gingival connective tissue was obtained from a healthy adult donor, tissue was minced for explant culture. The cultivated mesenchymal stem cells (MSCs) were expanded in vitro for 4 weeks and harvested. MSCs were aliquoted and cryopreserved. On the days of treatment, MSCs were thawed and prepared for intravenous administration. MSCs were suspended in 5 mL of normal saline for bolus injection. The patient received administration of MSCs (3 million/kg/infusion) for a total of five times in eight weeks. Gradual clearing of plaques was observed. A week after the last injection, psoriatic lesions were fully cleared. No adverse effect was reported or observed. The patient has been free of psoriasis for 5 years and 9 months till now (November 2022). Although autologous transplantation is a safe therapeutic option in immunogenicity, the quality and proliferation capacity of MSCs were often reduced due to age and existing illness in the patient. MSCs are inherently hypo-immunogenic due to low-level major histocompatibility complex (MHC) Class I expression and lack of expression of MHC Class II. The gingiva is a unique biological barrier of the periodontium. MSCs from gingiva express faster healing following injury or lesion, and excellent immuno-modulatory effect. They are multi-potent postnatal stem cells for live cell-based therapy in regenerative, frontier medicine, and dermatological disorders. In addition, MSC therapy has cured cases of multiple myeloma, renal failure, and multiple episodes of nephrolithiasis, and is a potential solution for coronavirus.