Psoriasis is a chronic skin disease characterized by the hyperproliferation of keratinocytes and an overactive autoimmune response. Photodynamic therapy (PDT) has been established as a promising intervention for alleviating psoriasis. However, the current transdermal delivery of photosensitizers is inefficient and imprecise. In this study, we developed a foamed microemulsion nanodroplets system containing chlorin e6 (Ce6 FM), exhibiting precise epidermal targeting and retention, which targeted the aberrantly proliferating epidermal cells at psoriatic skin lesions and avoided the damage to the normal cutaneous cells. Upon application in a psoriatic mouse model, Ce6 FM efficiently induced keratinocyte apoptosis by generating reactive oxygen species under laser. Furthermore, Ce6 FM-based PDT activated the cyclooxygenase-2-induced immunosuppressive pathway in keratinocytes, resulting in the amelioration of the autoimmune microenvironment in psoriatic skin. Additionally, Ce6 FM-based PDT did not induce skin damage or atrophy associated with non-targeted halometasone treatment. Overall, Ce6 FM-based PDT holds promise as an effective, safe and compliant strategy for psoriasis treatment.

Exosomes make a significant contribution during stem cell-based therapy due to the abundant contents. Accumulating evidence implies exosomes can act as potential biological nano agents. We herein propose hypoxic preconditioning for neural stem cells (NSCs) that could produce hypoxic exosomes for efficient treatment of ischemic stroke. Hypoxic preconditioning on NSCs significantly altered the miRNAs encapsulated in exosomes. Notably, hypoxic exosomes could target the injured brain to regulate the microenvironment to inhibit neuroinflammation and promote blood–brain barrier permeability recovery. Additionally, the autologous NSCs in Nestin-CreER mice could be activated by hypoxic exosomes to facilitate nerve regeneration. After hypoxic preconditioning, exosomes further exerted therapeutic effects on both survival (25%) and behavioral outcomes in ischemic stroke mice. Overall, hypoxic preconditioning NSCs can produce effective nano agent and may represent a promising strategy for clinical neurorestorative therapy.