Hydrogel microparticles (HMPs) are promising for biomedical applications, ranging from the therapeutic delivery of cells and drugs to the production of scaffolds for tissue repair and bioinks for 3D printing. Biologics (cells and drugs) can be encapsulated into HMPs of predefined shapes and sizes using a variety of fabrication techniques (batch emulsion, microfluidics, lithography, electrohydrodynamic spraying and mechanical fragmentation). HMPs can be formulated in suspensions to deliver therapeutics, as aggregates of particles (granular hydrogels) to form microporous scaffolds that promote cell infiltration or embedded within a bulk hydrogel to obtain multiscale behaviours. HMP suspensions and granular hydrogels can be injected for minimally invasive delivery of biologics, and they exhibit modular properties when comprised of mixtures of distinct HMP populations. In this Review, we discuss the techniques that are available for fabricating HMPs, as well as the multiscale behaviours of HMP systems and their functional properties, highlighting their advantages over traditional bulk hydrogels. Furthermore, we discuss applications of HMPs in the fields of cell delivery, drug delivery, scaffold design and biofabrication.

水凝胶微粒（HMP）在生物医学应用中前景广阔，从治疗性递送细胞和药物到生产用于组织修复的支架和用于3D打印的生物油墨，不一而足。可以使用多种制造技术（分批乳液，微流控，光刻，电动流体动力喷涂和机械破碎）将生物制剂（细胞和药物）封装到预定义形状和大小的HMP中。可以将HMPs配制成悬浮液以提供治疗剂，以颗粒（粒状水凝胶）的聚集体形式形成微孔支架，从而促进细胞浸润或嵌入散装水凝胶中以获得多尺度行为。可以注射HMP悬浮液和颗粒状水凝胶，以微创方式输送生物制剂，当由不同HMP群体的混合物组成时，它们表现出模块化的特性。在这篇综述中，我们讨论了可用于制造HMP的技术，以及HMP系统的多尺度行为及其功能特性，突出了其相对于传统本体水凝胶的优势。此外，我们讨论了HMP在细胞递送，药物递送，支架设计和生物制造领域的应用。