Musculoskeletal (MSK) disorders—osteoporosis, osteoarthritis, rheumatoid arthritis, intervertebral disc degeneration, tendinopathy, and skeletal muscle injury—contribute the largest share of years lived with disability worldwide. Conventional therapy relies on systemic dosing or repeated intra-articular and peri-tissue injections, which suffer from off-target toxicity, poor lesional bioavailability, and low adherence. Polymer microneedles (MNs)—micron-scale projections of biodegradable, dissolving, hydrogel-forming, or composite polymers—have rapidly matured into a versatile platform for minimally invasive, spatially localized, and temporally programmable delivery of small molecules, biologics, nucleic acids, extracellular vesicles, and cells to MSK tissues. This review synthesizes 2018–2026 advances in polymer MN systems engineered specifically for MSK regeneration. We classify dominant polymer chemistries and MN architectures; map fit-for-purpose across bone, cartilage, joint, intervertebral disc, tendon, and skeletal muscle; and survey “smart” MN designs that exploit reactive oxygen species, pH, mechanical, triboelectric, optogenetic, and ultrasonic triggers. We close with a concise conclusion and forward perspective that identifies the key design levers—hybrid MN–scaffold combination products, stimuli-responsive platforms tuned to the MSK micro-environment, and cell- and EV-loaded formats—most likely to have clinical impact.

Cultured meat aims to manufacture genuine animal tissue from cells in vitro, displacing the environmental and ethical liabilities of livestock slaughter. Because the final product must reproduce the fibre architecture, fat marbling, and nutrition of conventional meat, the cell—its identity, proliferative ceiling, and differentiation fidelity—is the central determinant of feasibility. This review consolidates the stem cell biology of cultured meat from a tissue engineering perspective. We first compare the principal cell sources: muscle satellite cells, which offer authentic myogenicity but limited expansion; pluripotent stem cells, which are effectively immortal but require directed differentiation; and mesenchymal, adipogenic, and fibro-adipogenic progenitors that supply fat and connective tissue. We then examine how myogenic and adipogenic commitment is controlled through growth-factor and small-molecule signalling, serum-free medium design, and co-culture strategies that recreate the multicellular composition of meat. We next survey biomaterial scaffolds—edible microcarriers, hydrogels, and decellularized plant matrices—that organize stem cells into anisotropic, perfusable, macroscale constructs, drawing on scaffold-design principles from regenerative medicine. Finally, we address bioreactor scale-up, medium cost, cell-line stability, and regulatory translation. We argue that cultured meat will advance fastest when cell source, differentiation protocol, and scaffold architecture are co-designed rather than optimized in isolation.