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DOI: 10.1002/admi.201801148 are commonly treated by inserting vascular prostheses at the occlusive vessel including artificial stents and grafts.[2] Currently, synthetic vessels are in significant demand by clinical patients because proper autologous grafts are very scarce due to the pre-existent vascular diseases.[3] Among the adopted biomaterials such as nylon, dacron, and polyurethane, expanded polytetrafluoroethylene (e-PTFE) is the most commonly used material to make large-caliber diameter artificial vessels in clinical.[4,5] However, because of the low blood compatibility of biomaterials in low flow and high resistance circulation, surface-induced thrombosis and embolization will seriously impair the long-term patency of the synthetic vessel in situations where the graft diameter is normally smaller than 6 mm. In order to avoid the formation of stenosis and thrombosis, an ideal artificial vessel must possess the biological characteristics similarly to the native ones with sufficient strength, cell compatibility, bioactivity, and biostability.[6] Investigations have demonstrated that surface modification of biomaterial has a profound influence on the interactions between the biological environment and artificial materials.[7–9] Endothelialization of biomaterials, for instance, could be significantly enhanced by altering the physical properties such as porosity, roughness, and hydrophilicity.[10] Therefore, a variety of methods including photochemical technique, micropattern printing, ion-beam irradiation, and plasma treatment[11–14] have been developed so far to modify the surface properties of biomaterials, making them more suitable for cell's adhesion, growth, and proliferation. However, all these methods have been limited to planar surfaces that are not suitable for direct inner-surface modification of artificial vessels. On the other hand, femtosecond laser-based processing is a powerful 3D fabrication technique that has demonstrated ultrahigh spatial resolution capability approaching to several nanometers as well as broad choices of material species.[15–19] For instance, sharp-spike-shaped black silicon fabricated by femtosecond laser can significantly enhance the absorption of silicon surfaces in a broadband spectrum resulting in Cardiovascular diseases, the leading cause of death worldwide in the last two decades, are mainly due to the pathological changes inside the heart or blood vessels. Current treatment prescription is to replace obstructed blood vessels by synthetic alternatives, but it can only cure patients effectually when the vessel diameter is larger than a certain value because the cell attachment capacity on a small-caliber artificial vessel is usually unacceptable for long-term patency. Here a femtosecond filamenting laser-based fabrication approach that can produce in situ microstructures on the inner surface of small-caliber tubules is reported. It is shown that the inner-surface fabrication with an aspect ratio as high as 10:1 can be achieved and the processed samples exhibit significant changes in physical properties including topography, roughness, hydrophobicity, as well as in biological property with improved ability for Hela cells to adhere and grow. The results provide a possibility toward fabricating small-caliber artificial vessels that might be suitable for long-term patency use.