Biomaterials for 3D Cell Biology Research Letter Three-dimensional nanofiber scaffolds with arrayed holes for engineering skin tissue constructs Lina Fu and Jingwei Xie, Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, Omaha, NE 68198, USA Mark A. Carlson, Department of Surgery-General Surgery, University of Nebraska Medical Center, Omaha, NE 68198, USA Debra A. Reilly, Department of Surgery-Plastic Surgery, University of Nebraska Medical Center, Omaha, NE 68198, USA Address all correspondence to J. Xie at jingwei.xie@unmc.edu (Received 20 April 2017; accepted 19 June 2017) Abstract Three-dimensional (3D) scaffolds composed of poly(ε-caprolactone) and gelatin nanofibers were fabricated by a combination of electrospin- ning and modified gas-foaming. Arrayed holes throughout the scaffold were created using a punch under cryo conditions. The crosslinking with glutaraldehyde vapor improved the water stability of the scaffolds. Cell spheroids of green fluorescent protein-labeled human dermal fibroblasts were prepared and seeded into the holes. It was found that the fibroblasts adhered well on the surface of nanofibers and migrated into the scaffolds due to the porous structures. The 3D nanofiber scaffolds may hold great potential for engineering tissue constructs for various applications. Introduction In the USA alone, chronic wounds affect 6.5 million patients and the associated cost for treating these wounds is about $25 billion each year. [1] Timely healing and closure is critical to reducing the cost and morbidity associated with chronic lower extremity wounds. [2] Debridement of the wound area and grafting with autologous split thickness grafts is still the gold standard for the treatment of chronic wounds. [3,4] However, the success rate of split thickness skin graft for heal- ing chronic wounds is low in the range 33–73%. [5] Besides, meshed skin grafts usually require large areas of donor skin tis- sues for wound coverage due to their limited expansion ratios, which causes the potential risks of donor site morbidity and poor wound healing unique to the diabetic state. [6] Microskin grafts (e.g., autograft islands and stamp autografts) are often associated with low acceptance rates and the severe scarring. [7] In addition, the interstices of the grafts tend to form hypertro- phic scarring. The ultimate goal of tissue engineering is to use a combina- tion of cells/tissues, engineered materials, and suitable bio- chemical and physical cues to restore, maintain, or improve biologic functions of damaged tissues or organs. [8] Tissue engi- neered skin grafts may provide an optimized solution to improved healing of chronic wounds. Our previous studies demonstrated the fabrication of a “sandwich-type” nanofiber- based skin graft through seeding minced skin tissues onto the microwells of nanofiber membrane and covering with a radially aligned nanofiber membrane. [9] Although nanofiber mem- branes were able to direct cell migration and achieve the full cell coverage on the surface of membranes in a short period of time, the nanofiber membranes used were mainly in 2D and cells only migrated on their surface. Recently, our group has developed a modified gas-foaming technique to expand 2D nanofiber membranes in the third dimension with controlled thickness and highly porous structures. [10,11] It was also dem- onstrated that cells can infiltrate the expanded nanofiber scaf- folds and proliferate within the nanofiber scaffolds. These promising results motivated us to fabricate a novel type nano- fiber skin graft for chronic wound healing. Our long-term goal is to use 3D expanded nanofiber scaffolds with arrayed holes together with minced autologous tissues (e.g., skin and bone) to form transplantable 3D tissue constructs for wound healing and bone regeneration. Compared with typical fibrous scaffolds (e.g., 2D nanofiber membranes and 3D expanded nanofiber scaffolds), it is expected that scaffolds with arrayed holes can greatly enhance cell penetration through- out the whole scaffold as the cells can migrate from both holes and surrounding areas of scaffolds (Fig. 1). The aim of the punched holes was to combine minced tissues (e.g., skin) with 3D expanded scaffolds for creation of 3D skin tissue constructs for wound healing and skin regeneration. To meet this goal, we firstly fabricated 2D nanofiber membranes using traditional electrospinning. [9,12] Comparing with poly(ϵ-caprolactone) (PCL), the blend with gelatin renders the fiber scaffolds better biocompatibility and faster degradation rate. [13] In order to pre- pare a highly hydrophilic 3D nanofibrous scaffold, we punched arrayed holes throughout 2D scaffolds and then transformed 2D membranes into 3D nanofiber scaffolds using a modified MRS Communications (2017), 7, 361–366 © Materials Research Society, 2017 doi:10.1557/mrc.2017.49 MRS COMMUNICATIONS • VOLUME 7 • ISSUE 3 • www.mrs.org/mrc ▪ 361 https://doi.org/10.1557/mrc.2017.49 Downloaded from https://www.cambridge.org/core. IP address: 207.241.231.82, on 26 Jul 2018 at 12:08:07, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms.