Speaker
Description
Digital Light Processing (DLP) is a 3D printing method that offers enhanced precision, quicker print times, increased throughput, and better cell viability by minimizing shear stress compared to extrusion-based bioprinting, which depends on mechanical nozzle deposition and tends to be slower with lower resolution. These advantages make it particularly well-suited for fabricating complex tissue structures. We have utilized this technology to fabricate knee meniscal constructs and corneal stroma equivalents (CSE). With Gelatin methacryloyl (GelMA) as the base material for both, we employed two different second crosslinking methods for each of these tissues to achieve the desired properties mimicking the native tissues. For printing meniscal constructs, we employed a post-printing crosslinking with tannic acid. The secondary tannic acid (TA) crosslinking not only resulted in mechanical properties closer to the native meniscal tissue (~200 kPa) but also showed excellent anti-bacterial, anti-oxidant and immunomodulatory properties. TA crosslinking did not affect the chondrogenic potential of GelMA, aided the differentiation of human Mesenchymal Stromal Cells (hMSCs) into chondrocytes. In addition, the anti-inflammatory cytokines such as IL-4, TGF-β1, and IL-10 were upregulated and the pro-inflammatory cytokines such as TNFα, MCP1, and IFNγ were down regulated when macrophages were cultured on TA-crosslinked constructs. We utilized Schiff’s base reaction as the secondary crosslinking method for printing of corneal constructs, by adding oxidized carboxy methyl cellulose (OxiCMC) to GelMA. DLP printing not only enabled printing of 6 constructs in 20 minutes with the corneal anisotropy included but also achieved the desirable properties of an ideal CSE. GelMA-OxiCMC bioink had a compressive modulus of ~110 kPa which is in the range of corneal modulus, exhibiting greater than 90% optical transmittance at 500nm. The human corneal keratocytes showed >94% viability post-printing, maintained their stellate morphology, and expressed characteristic markers such as keratocan and lumican.
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