Regenerative Medicine Entering a New Era

摘要

The development of biomedicine is always coupled with advances in technologies and materials. Regenerative medicine, which aims to repair injured or diseased tissues/organs, has become a multidisciplinary field covering both the basic and engineering fields of life sciences. The general strategy in regenerative medicine is the use of cells, together with materials, to eventually promote tissue healing or create replacement tissues. During this process, biomaterials serve as scaffolds and provide mechanical and biochemical cues to modulate cell behaviors. A representative example showing the significant roles of biomaterials is cell culture. Cells and tissues grown in three-dimensional (3D) frameworks more closely resemble the microenvironment in vivo than in traditional two-dimensional (2D) culture. In this respect, the properties of materials, including their chemical composition, micro/nano structure, mechanical feature, biocompatibility, and degradability, etc., are key parameters for the success of tissue engineering and regenerative medicine. In addition, the construction techniques also come into play, considering the requirement for patterning various cells and materials into specific geometries so as to better recapitulate features and functions of native tissues. Overall, the progress in regenerative medicine, throughout its development history, is greatly dependent on the joint efforts in life science, medicine, material science and engineering technologies. In the past few decades, a large number of new materials and technologies have emerged, propelling the field of regenerative medicine into a new era (Figure 1). On one hand, biomaterials are transcending from simple conformations into “smart” ones that can respond to the surrounding environmental stimuli, such as temperature, light, humidity, pH, and stress. These smart biomaterials lay the foundation for understanding complex cell–material interactions and provide rich methods for controlling cellular behaviors. On the other hand, biotechnologies and material processing technologies, including but not restricted to synthetic biology, micro/nano fabrication, electrospinning, 3D/4D printing, microfluidics, organ-on-a-chip, etc., have spurred the advance of tissue engineering. These techniques enable the design and rebuilding of tissue constructs with high resolution and better biomimicry of native tissues and organs. In this Special Issue of Small, we have assembled a collection of research works as well as viewpoints focusing on new technologies and biomaterials for regenerative medicine. This Special Issue has 21 original Research Articles and 9 Reviews that cover the latest progress in this field. Stimuli-responsive materials and smart sensors, actuators, and robotics, are favorable in biomedical fields. Pumera's group presents a light-driven microrobots for biofilm eradication (smll.202106612). Yu's group introduces “drawn-on-skin” sensors for electrophysiological health monitoring (smll.202107099). Shang's group summarizes the recent progress of smart film actuators in biomedical applications (smll.202105116). Zheng's group presents pH-responsive coatings for enhancing osteogenic differentiation (smll.202106056). Santos's group overviews stimuli-responsive biomaterials for the treatment of cardiovascular and cerebrovascular diseases (smll.202200291). Hydrogels and composite hydrogel materials possess unique advantages for regenerative medicine applications. Zhang's group demonstrates that a natural hydrogel showing pro-healing properties could enhance tendon regeneration (smll.202105255). Yu's group develops a hybrid hydrogel system for bone regeneration (smll.202107991). Burdick's group creates injectable granular hydrogels allowing for cell invasion (smll.202201115). Fan's group reviews programmable DNA hydrogels and their role as artificial extracellular matrix (smll.202107640). Other functional materials, including functional extracellular vesicles (Kim's