Hydrogel and Polymeric Scaffolds in Renal Tissue Engineering: A Review of Innovations in Regenerative Therapy

Abstract

Chronic kidney disease (CKD) affects approximately 10% of the global population and often progresses to end-stage renal disease (ESRD), for which dialysis and transplantation remain the primary treatments despite significant limitations. This review presents a comparative analysis of hydrogel-based and polymeric scaffold biomaterials used in renal tissue engineering. Materials are evaluated based on fabrication strategies, mechanical properties, degradation behaviour, biocompatibility, and reported in vitro and in vivo functional outcomes. Comparative assessment emphasizes quantitative indicators including renal cell viability, nephron-like organization, vascularization efficiency, fibrosis reduction, and functional markers such as erythropoietin secretion and creatinine clearance. Hydrogels such as gelatin methacrylate (GelMA), alginate, polyethylene glycol (PEG), and extracellular matrix (ECM)-derived materials demonstrate enhanced cell survival and tissue-specific differentiation, while polymeric scaffolds including polycaprolactone (PCL) and poly(lactic-co-glycolic acid) (PLGA) offer superior mechanical stability and vascular integration, with reported vascular density increases of up to ~50% and significant reductions in fibrotic markers in preclinical models. However, quantitative benchmarking across studies remains limited by non-uniform protocols, short implantation durations, and inconsistent outcome metrics. Ethical considerations, immunological responses, and patient-specific risks associated with stem cell–scaffold integration are also insufficiently addressed. The absence of standardized evaluation frameworks limits definitive conclusions regarding therapeutic readiness, underscoring the need for unified performance metrics and long-term in vivo validation to advance clinical translation.