Bone defects from trauma, tumour resection, infection, and degenerative disease remain a major clinical burden, and autografts face limitations of supply and donor-site morbidity. Three-dimensional (3D) printing offers a route to patient-specific, architecturally defined bone scaffolds, while biopolymers from natural sources provide biodegradability, biocompatibility, and extracellular matrix-mimicking cues consistent with sustainable, green biomaterials science. This review synthesises recent progress in 3D printing of biopolymer-based scaffolds for bone tissue engineering. We first examine the principal feedstocks—alginate, gelatin and gelatin methacryloyl, collagen, chitosan, silk fibroin, cellulose, and microbial polyesters—and their preparation, crosslinking chemistry, and printability. We then compare extrusion, light-based, and indirect printing technologies and the process–property relationships governing resolution, mechanical competence, and cell viability. Composite and functionalisation strategies, including biopolymer–bioceramic hybrids and controlled delivery of growth factors and antimicrobial agents, are analysed as routes to osteoinduction, vascularisation, and infection control. Finally, we evaluate translational performance in preclinical models and outline central challenges of vascularisation, mechanical–degradation matching, scalability, and regulatory standardisation. Biopolymer 3D printing is positioned as a ve rsatile, sustainable platform whose clinical maturation depends on integrated material, structural, and biological design.

Injectable cryogels have emerged as a transformative class of biomaterials that combine macroporosity, mechanical resilience, and shape‐memory properties to enable minimally invasive therapeutic delivery. Unlike conventional hydrogels, cryogels are fabricated through cryogelation—a sub‐zero polymerization process that generates interconnected macropores through ice crystal templating—endowing them with sponge‐like elasticity and the ability to withstand extreme compression and recover their original architecture upon injection. Over the past decade, injectable cryogels have evolved from simple porous scaffolds to sophisticated multifunctional platforms incorporating nanocomposites, bioactive molecules, and stimuli‐responsive elements for applications spanning bone and cartilage regeneration, stem cell delivery, cancer immunotherapy, and hemostatic wound healing. This review provides a comprehensive and critical analysis of recent advances in shape‐memory injectable cryogels, organized around five interconnected themes: (i) the physicochemical mechanisms governing shape‐memory behavior and material design strategies, (ii) emerging fabrication approaches including three‐dimensional printing–cryogelation hybrids and nanocomposite reinforcement, (iii) cryogel‐mediated stem cell delivery and tissue regeneration, (iv) immunomodulatory and vaccine platforms, and (v) hemostatic and wound‐healing applications. We critically evaluate how macro‐architectural features, mechanical tunability, and biochemical functionalization collectively dictate biological outcomes, and identify key challenges—including scalability, sterilization, regulatory pathways, and clinical translation—that must be addressed to realize the full therapeutic potential of injectable cryogels.

Osteosarcopenia, the concurrent deterioration of bone density and skeletal muscle mass and function, represents a growing clinical challenge in ageing populations worldwide. Conventional single-tissue therapeutic approaches fail to address the intricate biochemical and mechanical crosstalk between bone and muscle at their shared interface. Electrospun nanofibrous scaffolds offer a versatile platform capable of recapitulating the hierarchical architecture of the musculoskeletal extracellular matrix (ECM). This review critically examines current strategies for designing multi-layered electrospun scaffolds that simultaneously target bone and muscle regeneration within the context of osteosarcopenia. We discuss the pathophysiological basis of bone–muscle crosstalk, highlighting the shared roles of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis and chronic inflammation. To effectively mimic native tissues, we evaluate aligned compliant fibers (e.g., poly(ε-caprolactone) (PCL)-gelatin) for myogenic differentiation and random, stiffer mineralized fibers (e.g., poly(lactic-co-glycolic acid) (PLGA)/nano-hydroxyapatite (nHA)) for osteogenic differentiation. Furthermore, incorporating a gradient transition zone is strongly emphasized to minimize interfacial stress under physiological loading. Advanced electrospinning techniques—coaxial, emulsion, and melt electrowriting—are reviewed for spatially controlled and sequential delivery of vital growth factors like IGF-1 and bone morphogenetic protein-2 (BMP-2). Preclinical evaluation models are addressed, identifying a critical gap regarding the lack of aged and ovariectomised (OVX) composite defect animal models specific to osteosarcopenia. Finally, translational barriers, including manufacturing scalability and regulatory complexities, are evaluated. Thisreview proposes a unified design framework for osteosarcopenia-targeted scaffolds and identifies critical knowledge gaps requiring future investigation.