## 8 Clinical Studies  
Several clinical studies have demonstrated the promising therapeutic effects of various types of MSCs in psoriasis treatment. [PERSON] et al. used UC-MSCs to treat two patients with psoriasis vulgaris in prolonged remission. One patient received a single dose of UC-MSCs following autologous hematopoietic stem cell transplantation, resulting in complete skin recovery within 12 months and remaining without recurrences for 5 years post treatment. The second patient was administered three UC-MSC infusions over three weeks, followed by two additional infusions as a consolidation therapy, and remained symptom-free for four years [144]. Similar effects were observed in a study where a patient with severe plaque psoriasis received five weekly intravenous infusions of gingival-tissue-derived MSCs (GMSCs). They experienced a complete regression of psoriatic lesions and stable remission for up to three years [145]. Some clinical studies employed AD-MSCs. For instance, [PERSON] et al. investigated the use of autologous AD-MSCs in two patients, one with psoriasis vulgaris (PV) and the other with psoriatic arthritis (PA). The authors reported substantial improvements in both patients, as evidenced by decreased PASI scores and prolonged maintenance post treatment [146]. A recent study illustrated that two patients with moderate to severe psoriasis treated with monthly intravenous AD-MSC injections for three months achieved significant improvements. Their PASI scores reduced by half and the therapy was safe and well-tolerated during the yearly treatment [87]. Additionally, five patients experiencing psoriatic plaques underwent treatment with subcutaneous injections of allogeneic AD-MSCs. They all had considerable progress in skin thickness, redness, and scaling. The authors reported other improvements, such as reduced inflammatory markers in the dermis, demonstrating the modulation of inflammation and lack of adverse effects [147]. Other clinical studies have explored different sources and methods of MSC therapy for psoriasis. In one study, autologous stromal vascular fraction (SVF), which contains AD-MSCs, was used to treat a patient with severe psoriasis. During a year, his PASI score dropped dramatically from 50.4 to 0.3, with significant improvements in skin quality [148]. Likewise, mesenchymal-stem-cell-conditioned medium (MSC-CM) was applied topically in a patient suffering from scalp psoriasis. After a month-long application, the patient's Psoriasis Scalp Severity Index (PSSI) score decreased from 28 to 0. Their disease-free state lasted for six months, showcasing the potential for topical MSC-based therapies [149]. The immunomodulatory of effects of UC-MSCs have also been pointed out in several studies. [PERSON] et al. conducted a phase 1/2a clinical trial in 2022 where 17 patients with psoriasis received a UC-MSC infusion, resulting in a 47.1% PASI improvement in some, including 35.3% who experienced over a 75% PASI improvement. This study also further showed immunomodulation of the immune responses, characterized by increases in Tregs and memory T cells while reducing Th17 cells and serum IL-17 levels [150]. Similarly, [PERSON] et al. performed a treatment on a patient who suffered from psoriasis and aplastic anemia using UC-MSCs in tandem with allogenic bone marrow transplantation for graft-versus-host disease prophylaxis; this resulted in the complete remission of psoriasis, and no recurrence was seen in the 150 days post-transplant [151]. There have also been clinical studies that have evaluated the safety and efficacy of adipose-tissue-derived MSC-Exo for the treatment of psoriasis. In one phase I/II clinical study, patients were administered exosomes intradermally at three dosages (50 \(\upmu\)g, 100 \(\upmu\)g, and 200 \(\upmu\)g per cm\({}^{2}\) of psoriatic skin), and the results were examined using the Target Lesion Assessment Score (TLAS), histopathological analysis, and immunohistochemistry.