Ho Eric, Li David Xinzheyang, Cui Hong, Akbar Dania, Siu Ricky, Morshead Cindi M, Chatenet David, Shoichet Molly S
Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON, M5S 3E5, Canada.
Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON, M5S 3G9, Canada.
Adv Healthc Mater. 2025 Sep;14(24):e2500765. doi: 10.1002/adhm.202500765. Epub 2025 Jul 11.
Following ischemic stroke, astrocytes and microglia become activated and create a hostile microenvironment that can exacerbate brain damage, yet these cells also contribute to tissue regeneration. Pituitary adenylate cyclase activating polypeptide (PACAP) is a promising neuroprotective peptide that modulates microglia toward a pro-reparative phenotype, however, its short half-life in vivo and dose-limited off-target effects have made systemic delivery untenable. Local delivery presents a promising alternative. To this end, we developed a hydrogel-nanoparticle composite for the minimally invasive, local delivery of PACAP to the brain and tested this strategy in chemically-induced, endothelin-1 stroke-injured mice. We demonstrate that prolonged delivery of PACAP improved the physical strength and mobility of mice for up to 28 days after stroke. The treatment decreased the number of apoptotic neurons in the stroke microenvironment, increased neuron survival at 28 days post-stroke, and attenuated reactive astrogliosis and microglia activation. PACAP stimulation resulted in increased Iba1Arg1 pro-reparative microglia and decreased Iba1CD86 pro-inflammatory microglia. Furthermore, PACAP stimulation significantly decreased pro-inflammatory GFAPLCN2 and GFAPS100β astrocytes versus controls. This phenotypic shift in microglia and astrocytes may account for the functional improvements post stroke and paves the way for local delivery of new therapeutic strategies targeting the immune response for stroke treatment.
缺血性中风后，星形胶质细胞和小胶质细胞被激活，形成一个可能加剧脑损伤的不利微环境，但这些细胞也有助于组织再生。垂体腺苷酸环化酶激活多肽（PACAP）是一种有前景的神经保护肽，可将小胶质细胞调节为促修复表型，然而，其在体内的半衰期短以及剂量受限的脱靶效应使得全身给药难以实现。局部给药是一种有前景的替代方法。为此，我们开发了一种水凝胶-纳米颗粒复合材料，用于将PACAP微创局部递送至大脑，并在化学诱导的内皮素-1中风损伤小鼠中测试了该策略。我们证明，在中风后长达28天的时间里，持续递送PACAP可改善小鼠的体力和活动能力。该治疗减少了中风微环境中凋亡神经元的数量，增加了中风后28天的神经元存活率，并减轻了反应性星形胶质细胞增生和小胶质细胞激活。PACAP刺激导致Iba1Arg1促修复小胶质细胞增加，Iba1CD86促炎小胶质细胞减少。此外，与对照组相比，PACAP刺激显著降低了促炎GFAPLCN2和GFAPS100β星形胶质细胞。小胶质细胞和星形胶质细胞的这种表型转变可能是中风后功能改善的原因，并为针对中风治疗的免疫反应的新治疗策略的局部递送铺平了道路。
