Advances in microneedle design for the delivery of drugs, proteins, and cells in the treatment of hypertrophic scars.

Hypertrophic scars (HS) represent a significant clinical challenge due to their complex pathophysiology and resistance to conventional therapies, often resulting in persistent symptoms such as itching, pain, and impaired joint mobility that compromise patients' quality of life. Current treatment modalities, including compression therapy, pharmacological agents, radiation, silicone gel, and laser therapies, have faced limitations primarily due to inadequate drug penetration into the dense fibrotic scar tissue. In this context, microneedle-mediated controlled delivery systems have emerged as a promising pharmaceutical platform to enhance localized and sustained delivery of therapeutic agents, including small-molecule drugs, biologic proteins, small interfering RNA, and living cells, directly into HS. This article critically reviews the biological and formulation-related challenges associated with transdermal delivery in scar tissue and highlights recent innovations in microneedle design, material selection, and drug-loading techniques tailored for controlled release applications. Furthermore, it discusses the integration of proteins and cell-based therapies within microneedle platforms and their potential to modulate scar remodeling and inflammation. By addressing current limitations and exploring cutting-edge technologies, this review article aims to guide the development of effective microneedle-mediated strategies for pharmaceutical intervention in hypertrophic scar management.