Associate Professor New Jersey Institute of Technology Newark, New Jersey, United States
Introduction: Extrusion-based 3D printing of biodegradable pol-ymers have been commonly used to fabricate tis-sue engineering scaffolds with large pores (~500 μm). However, these scaffolds often face challenges such as low cell retention and lack of spatial control over seeded cells or presentation of bioactive cues, which are crucial for interface tissue engineering. To address these challenges, a hybrid 3D printing approach has been proposed. This method integrates airbrushed fibrous gelatin methacrylate (GelMA) hydrogel membranes into 3D printed polycaprolactone (PCL) scaffolds. By adjusting the fiber density of the membranes, control over the distribution of seeded stem cells within the 3D scaffolds is achieved. Additionally, GelMA membranes serve the purpose of delivering biological cues to spatially control stem cell differentiation. This approach holds significant promise for enabling precise spatial control of cell distribution and modulating cellular behavior, particularly in the creation of 3D scaffolds for tissue interfaces such as osteochondral tissue. Such advancements are crucial for enhancing tissue engineering strategies and ultimately improving outcomes in regenerative medicine.
Materials and
Methods: Scaffolds were fabricated by melt extrusion 3D printing of PCL pellets (Mw = 55,000 g/mol, Scien-tific Polymer) at 80oC. Airbrushing solution was prepared by dissolving either Gel or GelMA in Ace-tic acid solution (90%, v/v). The concentration of solution, applied pressure, and airbrushing time were varied to optimize airbrushing parameters. For cell studies, hMSC (Lonza) were cultured on the scaffolds which were coated with a fibronectin solution.
Results, Conclusions, and Discussions:
Results: Hybrid scaffolds were fabricated by airbrushing Gel or GelMA within 3D printed layers of PCL scaffold. In one example, GelMa was airbrushed, forming a fibrous membrane, on top of 2 layers of 3D printed PCL scaffold, and this process was repeated as needed to develop a large-scale scaffold. The fiber density was controlled by adjusting airbrushing parameters to create high density (~63%) and low density (~36%) membranes (Fig. 1A) leading to permissive or inhibitory effect towards stem cell penetration and infiltration. The optical and SEM images in Fig. 1B depict GelMA fibrous membranes with a fiber diameter of ~0.7 μm. These membranes were crosslinked with glutaraldehyde, and methacrylates were utilized to attach peptides containing cysteine moieties, such as the integrin binding RGD peptide. Confocal images (Fig. 1C) further demonstrate that stem cells were able to attach and proliferate well on the fibrous membrane. The low cell seeding efficiency, attributed to the coarse microstructure of the scaffolds, was significantly enhanced by the membrane layer.
Conclusions and Ongoing Work: The successful development of gelatin/PCL and GelMA/PCL hy-brid scaffolds represents a significant advance-ment in controlling seeded stem cell distribution within tissue engineering scaffolds. The use of gelatin and gelatin methacrylate (GelMA) fibrous membranes in this study is aimed at not only spatially controlling seeded cell distribution but also temporally controlling biological cues. These cues include the spatial delivery of growth factors such as BMP-2 and TGF-β, which play crucial roles in regulating stem cell osteogenesis and chondrogenesis. This strategy holds great potential for applications in regenerative medicine, particularly in the development of scaffolds for bone and cartilage tissue engineering, where precise control over cell distribution and differentiation is essential for successful tissue regeneration.
Acknowledgements (Optional): We acknowledge the funding from NSF (CAREER Award #204479).
