Electrospun Polyurethane/Alginate–Chondroitin Sulfate Scaffolds for Chondrogenesis Publisher

Summary: Could a new scaffold help repair cartilage? Lab tests of polyurethane–alginate with chondroitin sulfate improved strength and cartilage markers; animal tests remain needed. #Cartilage #Biomaterials

Rostamani H ; Rafienia M ; Fakhraei O ; Poursamar A ; Mahdizadeh N
Source: Materials Chemistry and Physics Published:2026

Abstract

Articular cartilage defects are common clinical problems with limited intrinsic repair capacity, and conventional treatments such as autologous or allogeneic grafting and alloplastic implants remain constrained by donor-site morbidity, immunogenicity, and poor integration. Polyurethane (PU) as a biocompatible synthetic elastomer and alginate as a hydrophilic polysaccharide provide a suitable combination for the fabrication of blended scaffolds for tissue engineering. To improve the biological properties of the scaffold, chondroitin sulfate (CS) has been used as a chondrogenesis-stimulating additive. In this research, fibrous scaffolds were prepared through electrospinning of PU in tetrahydrofuran and alginate containing CS in acetic acid/distilled water. The physicochemical and mechanical characteristics of the scaffolds were evaluated. Then, cellular studies including cytotoxicity, adhesion, GAG quantification, RT-qPCR, and safranin-O staining using chondrocyte cells were performed to assess extracellular matrix formation. Random morphology was more suitable due to greater compatibility of pores and fiber diameter with natural cartilage tissue. The incorporation of CS made the surface more polar, lowering the water contact angle from ∼80° for PU/alginate to 61° at 1.0 wt% CS, and led to better cell attachment. Among the CS addition methods, the blending method with the main solution, while maintaining fiber uniformity and stable release, provided stronger cellular responses and healthier porous architecture. Among the CS incorporation levels tested, 0.5–1.0 wt% achieved a favorable balance between wettability, pore preservation, and biological efficiency, reflecting an effective CS loading rather than optimization of the full scaffold formulation. Dry-state peak stress rose from 1.03 MPa (CS-free) to a maximum of 1.35 MPa at 1.0 wt% CS before easing to 1.25 MPa at 1.5 wt%, and the 1.0 wt% scaffold retained ∼93% of its dry peak stress after hydration, against 62% for the CS-free control. GAG normalized to DNA at day 21 increased from 1.97 to ∼3.4-3.6 μg/μg, peaking at 1.0-1.5 wt% CS, with approximately 3-, 4-, and 6.5-fold upregulation of SOX9, ACAN, and COL2A1. The random PU/alginate scaffold with CS blended at 1.0 wt% (within the 0.5–1.0 wt% window) shows promise as a candidate for articular cartilage repair. Therefore, further research should be conducted to evaluate these findings in an in vivo environment. © 2026 Elsevier B.V.