Functionalized silk fibers from transgenic silkworms for wound healing applications: Surface presentation of bioactive epidermal growth factor.

Growth factors play a crucial role in wound healing in general and are promising tools for the treatment of chronic wounds as they can restore the physiological wound healing process. In growth factor-loaded wound dressings, human epidermal growth factor (EGF) is released in a burst and washed out quickly. The developed matrix consists of recombinant EGF produced in transgenic silkworms as a fusion protein with the fibroin light chain. The covalent linkage prevents EGF from draining into the surrounding tissue while presenting the growth factor on the surface. EGF-functionalized silk membranes and nonwovens lead to a 2.5-fold increase in the cell number of fibroblasts, while retaining full bioactivity even after e-beam sterilization. EGF is long-term presented without burst release and significantly reduces the wound area by 15% in an in vitro wound model. Hence, the cost-effective production of a biomaterial using transgenic silkworm larvae in combination with a growth factor paves the way for a promising new multifactorial wound cover for chronic wound healing. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2643-2652, 2018.

Weaving for heart valve tissue engineering.

Weaving is a resourceful technology which offers a large selection of solutions that are readily adaptable for tissue engineering (TE) of artificial heart valves (HV). The different ways that the yarns are interlaced in this technique could be used to produce complex architectures, such as the three-layer architecture of the leaflets. Once the assembly is complete, growth of cells in the scaffold would occur in the orientation of the yarn, enabling the deposition of extra cellular matrixes proteins in an oriented manner. Weaving technology is a rapidly evolving field that, first, needs to be understood, and then explored by tissue engineers, so that it could be used to create efficient scaffolds. Similarly, the textile engineers need to gain a basic understanding of key structural and mechanical aspects of the heart valve. The aim of this review is to provide the platform for joining these two fields and to enable cooperative research efforts. Moreover, examples of woven medical products and patents as well as related publication are discussed in this review, nevertheless due to the large, and continuously growing volume of data, only the aspects strictly associated with HVTE lay in the scope of this paper.

A poly(lactic acid-co-caprolactone)-collagen hybrid for tissue engineering applications.

A biodegradable hybrid scaffold consisting of a synthetic polymer, poly(lactic acid-co-caprolactone) (PLACL), and a naturally derived polymer, collagen, was constructed by plastic compressing hyperhydrated collagen gels onto a flat warp-knitted PLACL mesh. The collagen compaction process was characterized, and it was found that the duration, rather than the applied load under the test conditions in the plastic compression, was the determining factor of the collagen and cell density in the cell-carrying component. Cells were spatially distributed in three different setups and statically cultured for a period of 7 days. Short-term biocompatibility of the hybrid construct was quantitatively assessed with AlamarBlue and qualitatively with fluorescence staining and confocal microscopy. No significant cell death was observed after the plastic compression of the interstitial equivalents, confirming previous reports of good cell viability retention. The interstitial, epithelial, and composite tissue equivalents showed no macroscopic signs of contraction and good cell proliferation with a two- to threefold increase in cell number over 7 days. Quantitative analysis showed a homogenous cell distribution and good biocompatibility. The results indicate that viable and proliferating multilayered tissue equivalents can be engineered using the PLACL-collagen hybrid construct in the space of several hours.