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In this paper we designed a STEM outreach program with a modular tissue engineering education tool (we refer to as “modular cyclic-stretch device”) to engage high school students in STEM hands-on activities. Using simple machines such as gears and rotating cams, students were able to build a custom device to apply cyclic stretch to biomaterials. With the help of this hands-on activity, our outreach program helped students grasp tendon tissue biomechanics and understand the importance of applying biomechanical force to regenerate tendon tissue in a laboratory setting. The two-day outreach program comprised: 1. pre- and post-tests; 2. lectures; 3. laboratory sessions, including the microscopic examination of stained tissue sections and a hands-on group activity employing the modular cyclic-stretch device; and 4. homework. Assessment results suggest that our program supports improved student awareness and interest in tissue engineering as a future profession. The program elevated students’ confidence in their ability to apply engineering principles to tasks such as building a modular cyclic-stretch device and measuring the mechanical properties of biological tissues. Building an educational bioreactor improved students’ understanding of the dynamic nature of the human body and the importance of tissue engineering as an emerging discipline towards replacing or regenerating damaged organs. We propose that our modular device has great outreach potential to introduce tissue engineering concepts to high school and potentially college freshmen engineering students.

The integration of titanium (Ti)-based implants with bone is limited, resulting in implant failure. This lack of osteointegration is due to the foreign body response (FBR) that occurs after the implantation of biodevices. The process begins with protein adsorption, which is governed by implant surface properties, e.g., chemistry, charge, wettability, and/or topography. The distribution and composition of the protein layer in turn influence the recruitment, differentiation, and modulation of immune and bone cells. The subsequent events that occur at the bone–material interface will ultimately determine whether the implant is encapsulated or will integrate with bone. Despite the numerous studies evaluating the influence of surface properties in the various stages of the FBR, the factors that affect tissue–material interactions are often studied in isolation or in small correlations due to the technical challenges involved in assessing them in vitroor in vivo. Consequently, the influence of protein conformation on the Ti bone implant surface design remains an unresolved research question. The objective of this review is to comprehensively evaluate the existing literature on the effect of surface parameters of Ti and its alloys in the stages of FBR, with a particular focus on protein adsorption and osteoimmunomodulation. This evaluation aims to systematically describe these effects on bone formation.

Abstract: Bioreactors have immense value within tissue engineering by enabling important control over design inputs within a microenvironment; however, they are often complex and expensive. Herein, we demonstrate a strategy where a bioreactor was 3D-printed as a means to provide an accessible route to culture scaffolds under physiological inputs and to determine an ideal tendon scaffold structure based on remodeling and degradation events. Furthermore, real-time monitoring of tissue remodeling is introduced through the bioreactor design. Following in vitro uniaxial stretch conditioning, scaffolds were positively altered to reflect improved biomechanical function, enhanced extracellular matrix (ECM) content, and increased mechanical properties of elastic moduli. A bioreactor was constructed to meet the following criteria: real-time readout of resistance, ability to be easily cleaned and sterilized, control of strain, speed, and time parameters, and capability to withstand 3 weeks of continuous load with minimal maintenance. The scaffolds cultured in a dynamic setting showed improved mechanics and promising ECM and collagen content generated. Overall, the bioreactor was effective as a tool to provide mechanical culture conditions that promote the tendon cell niche. The bioreactor supports the scaffolds as a possible therapeutic venture in tendon tissue engineering. Additionally, the 3D-printed bioreactor is a significant contribution to the tissue engineering field by making dynamic culturing more accessible for researchers. Lay Summary: Bioreactors present physiological and dynamic conditions for tissue testing and are crucial in tissue engineering for product development, standardization, quality control, and large-scale synthesis. The low-cost, 3D-printed, programmable bioreactor provides cyclic stretch to scaffolds with real-time resistance readout and demonstrates tissue changes over time. The bioreactor enhances scaffold biomechanics and biofunctionality towards natural tendon by promoting cell alignment through mechanical force. The design components are culture chamber for tendon constructs, motor control of uniaxial stretching, and a base for stabilization. The results from conditioning scaffolds in the bioreactor lend to a better understanding of how specific inputs affect tissue outcomes.

Orthopedic implants rely on facilitating a robust interaction between the implant material surface and the surrounding bone tissue. Ideally, the interface will encourage osseointegration with the host bone, resulting in strong fixation and implant stability. However, implant failure can occur due to the lack of integration with bone tissue or bacterial infection. The chosen material and surface topography of orthopedic implants are key factors that influence the early events following implantation and may ultimately define the success of a device. Early attachment, rapid migration and improved differentiation of stem cells to osteoblasts are necessary to populate the surface of biomedical implants, potentially preventing biofilm formation and implant-associated infection. This article explores these early stem cell specific events by seeding human mesenchymal stem cells (MSCs) on four clinically relevant materials: polyether ether ketone (PEEK), Ti6Al4V (smooth Ti), macro-micro rough Ti6Al4V (Endoskeleton®), and macro-micro-nano rough Ti6Al4V (nanoLOCK®). The results demonstrate the incorporation of a hierarchical macro-micro-nano roughness on titanium produces a stellate morphology typical of mature osteoblasts/osteocytes, rapid and random migration, and improved osteogenic differentiation in seeded MSCs. Literature suggests rapid coverage of a surface by stem cells coupled with stimulation of bone differentiation minimizes the opportunity for biofilm formation while increasing the rate of device integration with the surrounding bone tissue.

The free energy involved in the formation of an interface between two phases (e.g., a solid–liquid interface) is referred to as the interfacial free energy. For the case of solidification, the interfacial free energy dictates the height of the energy barrier required to nucleate stable clusters of the newly forming solid phase and is essential for producing an accurate solidification kinetics model using classical nucleation theory (CNT)-based methods. While various methods have been proposed for modeling the interfacial free energy for solid–liquid interfaces in prior literature, many of these formulations involve making restrictive assumptions or approximations, such as the system being at or near equilibrium (i.e., the system temperature is approximately equal to the melt temperature) or that the system is at pressures close to atmospheric. However, these approximations and assumptions may break down in highly non-equilibrium situations, such as in dynamic-compression experiments where metastable liquids that are undercooled by hundreds of kelvin or overpressurized by several gigapascals or more are formed before eventually solidifying. We derive a solid–liquid interfacial free-energy model for such high-pressure conditions by considering the enthalpies of interactions between pairs of atoms or molecules. We also consider the contribution of interface roughness (disordering) by incorporating a multilayer interface model known as the Temkin n-layer model. Our formulation is applicable to a diverse variety of materials, and we demonstrate it by developing models specifically for two different materials: water and gallium. We apply our interfacial free-energy formulation to CNT-based kinetics simulations of several suites of dynamic-compression experiments that cause liquid water to solidify to the high-pressure solid polymorph ice VII and have found good agreement to the observed kinetics with only minor empirical fitting.

This paper describes the development of a novel low‐cost and efficient method, 3D near‐field electrospinning, to fabricate high‐resolution, and repeatable 3D polymeric fiber patterns on nonconductive materials with potential use in tissue engineering. This technology is based on readily available hobbyist grade 3D printers. The result is exquisite control of the deposition of single fibers in an automated manner. Additionally, the fabrication of various fiber patterns, which are subsequently translated to unique cellular patterns, is demonstrated. Finally, poly(methyl methacrylate) fibers are printed within 3D collagen gels loaded with cells to introduce anisotropic properties of polymeric fibers within the cell‐loaded gels. 3D Near‐Field Electrospinning (3DNFES) is a new method for printing polymeric fibersin highly organized, controlled, and reproducible manner. 3DNFES offers several significant advantages including: (1) producing precise patterns of fibers on relatively large‐scale area, (2) printing in all three directions, (3) offering an inexpensive method, and (4) readily combines with other prepatterned nanostructures or microstructures such as gels.

3D near‐field electrospinning is capable of depositing single nano‐ and microfibers with extraordinary precision. This image demonstrates a stem cell attached to perpendicular microfibers. As described by Justin L. Brown and co‐workers in article number 1700456, this process can be multiplexed with other 3D printing techniques to build a wide array of complex structures for applications, such as, regenerative medicine.