Erythropoietin Nanobots: Their Feasibility for the Controlled Release of Erythropoietin and Their Neuroprotective Bioequivalence in Central Nervous System Injury

Background: Erythropoietin (EPO) plays important roles in neuroprotection in central nervous system injury. Due to the limited therapeutic time window and coexistence of hematopoietic/extrahematopoietic receptors displaying heterogenic and phylogenetic differences, fast, targeted delivery agents, such as nanobots, are needed. To confirm the feasibility of EPO-nanobots (ENBs) as therapeutic tools, the authors evaluated controlled EPO release from ENBs and compared the neuroprotective bioequivalence of these substances after preconditioning sonication. Methods: ENBs were manufactured by a nanospray drying technique with preconditioning sonication. SH-SY5Y neuronal cells were cotreated with thapsigargin and either EPO or ENBs before cell viability, EPO receptor activation, and endoplasmic reticulum stress-related pathway deactivation were determined over 24 h. Results: Preconditioning sonication (50-60 kHz) for 1 h increased the cumulative EPO release from the ENBs (84% versus 25% at 24 h). Between EPO and ENBs at 24 h, both neuronal cell viability (both > 65% versus 15% for thapsigargin alone) and the expression of the proapoptotic/apoptotic biomolecular markers JAK2, PDI, PERK, GRP78, ATF6, CHOP, TGF-beta, and caspase-3 were nearly the same or similar. Conclusion: ENBs controlled EPO release in vitro after preconditioning sonication, leading to neuroprotection similar to that of EPO at 24 h.