Liposomes for drug delivery in stroke.

Stroke is one of the leading causes of mortality and morbidity worldwide. Due to its poor prognosis, there is a major negative impact on the patients and their family's life quality. However, despite the severity of this pathology tissue plasminogen activator (tPA) is the only FDA approved treatment for ischemic stroke. Moreover, there is no effective treatment for hemorrhagic stroke and only some palliative procedures are often performed to improve the patient's quality of life. Considering this, nanotechnology can offer some advantages for the development of new therapies for stroke. Among the various types of nanomaterials, liposomes are the most extensively studied due to their biocompatibility, biodegradability, and low toxicity. Liposomes, as a drug delivery system, are able to mask therapeutic compounds and allow their passage through the blood-brain barrier. Liposomes also protect drugs from degradation in a biological environment, increasing the circulation time and accumulation in the target tissue. Hence, this review highlights the potential of liposomes applications for delivery of therapeutic compounds for treating stroke.

ECM hydrogel for the treatment of stroke: Characterization of the host cell infiltrate.

Brain tissue loss following stroke is irreversible with current treatment modalities. The use of an acellular extracellular matrix (ECM), formulated to produce a hydrogel in situ within the cavity formed by a stroke, was investigated as a method to replace necrotic debris and promote the infiltration of host brain cells. Based on magnetic resonance imaging measurements of lesion location and volume, different concentrations of ECM (0, 1, 2, 3, 4, 8 mg/mL) were injected at a volume equal to that of the cavity (14 days post-stroke). Retention of ECM within the cavity occurred at concentrations >3 mg/mL. A significant cell infiltration into the ECM material in the lesion cavity occurred with an average of ∼36,000 cells in the 8 mg/mL concentration within 24 h. An infiltration of cells with distances of >1500 µm into the ECM hydrogel was observed, but the majority of cells were at the tissue/hydrogel boundary. Cells were typically of a microglia, macrophage, or neural and oligodendrocyte progenitor phenotype. At the 8 mg/mL concentration, ∼60% of infiltrating cells were brain-derived phenotypes and 30% being infiltrating peripheral macrophages, polarizing toward an M2-like anti-inflammatory phenotype. These results suggest that an 8 mg/mL ECM concentration promotes a significant acute endogenous repair response that could potentially be exploited to treat stroke.