Biliary stricture is defined as the reduction and narrowing of the bile duct lumen, which can be caused by many factors such as cancer and inflammation. Biliary stent placement can effectively alleviate benign and malignant biliary strictures. However, the commonly used plastic or metallic biliary stents are far from ideal and do not satisfy all clinical requirements，although several types of biodegradable biliary stents have been developed and used clinically. In this review, we summarized current development status of biodegradable stents with the emphasis on the stent materials. We also presented the future development trends based on the published literature.

A series of adjustable long chain branching poly(L-lactide)s (b-PLAs) was prepared by reactive processing of linear PLA using pyromellitic dianhydride (PMDA) and polyfunctional epoxy ether (PFE) as the branching agent and their vascular stents were fabricated via 3D-printing. Fourier-transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC) results indicated that the chain branching reaction occurs and the average molecular weight increases obviously after the chain branching reaction. Rheological tests on the b-PLAs demonstrated that they are composed of a symmetric- or asymmetric-star, or tree-like chain configuration. The volume fraction of the branching structure of the chains increased from 0.03 to 0.3 with increasing branching agent content. The effects of the branching structure on the melt crystallization behavior of b-PLAs were investigated by means of differential scanning calorimetry (DSC). The isothermal crystallization results showed that the half-time of crystallization (t_1/2) of the samples decreased from 16.8 min for linear PLA to 2.3 min when the branching agent content was 2 wt% at 106 °C. Also, as observed from polarized optical microscopy experiments, the nucleation density of the b-PLAs significantly increased with increasing volume fraction of the branching structure because the enrichment of segments around the branching structure facilitated nucleation, thus the b-PLA samples have a higher probability to form a primary nucleus than linear PLA. Moreover, mechanical testing demonstrated that forming the branching structure enabled the effective modification of the mechanical properties of PLA. The microstructures with a smaller spherulite size and higher crystallinity of the b-PLAs improved their tensile strength and modulus from 45.7 MPa and 1.63 GPa to 77.2 MPa and 3.41 GPa, respectively. Furthermore, the radial force performance of the 3D printed b-PLA vascular stents was enhanced from 4.8 to 13.7 N by the branching structure of the chains. The CCK-8 assay results indicated that the osteoblast activity of b-PLA is higher than that of linear PLA, and the scanning electron microscopy (SEM) results also indicated that b-PLA was covered and flattened with a better attachment morphology for the osteoblasts than PLA. Therefore, the b-PLAs with a long chain branching structure could effectively facilitate cell growth, proliferation, and differentiation.

The blends of poly(L-lactide acid-p-dioxanone-glycolide) (PLPG) with poly(D-lactide) (PDLA) (PLPG/PDLA) were prepared by a solution-casting method. The effects of PDLA on the properties of the PLPG were studied. DSC and WAXD results confirmed that PLA stereocomplex (sc-PLA) crystals were formed by blending PLLA segments in PLPG with PDLA, and the melting endotherm for both PLLA and sc-PLA relied on PDLA content. The non-isothermal crystallization results indicated that the crystallization process was remarkably accelerated by the addition of PDLA. Meanwhile, the results of isothermal crystallization indicated that the half-time of crystallization decreased with the increase of PDLA content. Besides, the enzymatic degradation behavior of the samples showed that with the increase of PDLA content, the mass loss gradually decreased. Furthermore, TGA and DTG results indicated that the thermal degradation of the samples was a complex process. Moreover, the biocompatibility of the samples was tested by cell culture and using CCK-8 and live/dead staining. Results showed that the samples possessed lower cytotoxicity. Therefore, the PLPG/PDLA blends are promising candidate materials in biomedical applications.

The membranes of poly(l-lactide acid-p-dioxanone-glycolide) (PLPG) with stereocomplex poly(lactic acid) (sc-PLA) were prepared by the solution blending way. It was observed that sc-PLA significantly heightened the crystallizing behavior of PLLA segments of the PLPG matrix. The crystallizing behavior displayed that the temperature of crystallization shifted to a higher range than that of PLPG. Moreover, the half-time of crystallization sharply decreased in value as the sc-PLA content increased in value on account of the pre-eminent nucleation ability of sc-PLA. TGA results revealed the thermal stability of the samples with the increase of sc-PLA compared to PLPG. Meanwhile, enzymatic degradation results indicated that the mass loss rate of the membrane decreased with the introduction of sc-PLA, but the overall degradation ability was still greater than that of PLLA. In the meantime, the biological experiment indicated that the membrane possessed low cytotoxicity.

Bioresorbable vascular stents (BVSs) offer a transformative therapeutic advantage over permanent metal stents by temporarily supporting the vessel and then fully degrading, thereby restoring natural vasomotion and eliminating long-term complications. However, their clinical translation has been hampered by inherent limitations of conventional manufacturing, including restricted material selection, inflexible design, and limited capability for functional integration. Three-dimensional (3D) printing emerges as a pivotal technology to address these challenges, enabling the fabrication of stents with customized architectures, complex structures, and integrated multifunctionality. This review systematically highlights the latest progress in 3D-printed BVSs, focusing on their evolution toward patient-specific, novel-structured, functional, and smart devices. It assesses advanced printing technologies, presents preclinical outcomes and preliminary clinical evidence of 3D-printed BVSs, discusses current challenges, and also provides some future research directions. By framing the current state of the art, this review aims to accelerate the development of next-generation vascular implants.