Challenges in engineering large customized bone constructs

Abstract

The ability to treat large tissue defects with customized, patient-specific scaffolds is one of the most exciting applications in the tissue engineering field. While an increasing number of modestly sized tissue engineering solutions are making the transition to clinical use, successfully scaling up to large scaffolds with customized geometry is proving to be a considerable challenge. Managing often conflicting requirements of cell placement, structural integrity, and a hydrodynamic environment supportive of cell culture throughout the entire thickness of the scaffold has driven the continued development of many techniques used in the production, culturing, and characterization of these scaffolds. This review explores a range of technologies and methods relevant to the design and manufacture of large, anatomically accurate tissue-engineered scaffolds with a focus on the interaction of manufactured scaffolds with the dynamic tissue culture fluid environment. Biotechnol. Bioeng. 2017;114: 1129-1139. © 2016 Wiley Periodicals, Inc.

Functional bioreactor characterization to assess potentials of nanocomposites based on different alginate types and silver nanoparticles for use as cartilage tissue implants

“…Medium flowrate of 0.12 mL/min corresponds to the superficial velocity of 18 μm/s calculated with respect to the disc base area, which is in the range of blood velocities in capillaries of 10–100 μm/s. Although the adult articular cartilage is largely avascular some fluid flow arises during cartilage compression in the course of daily activities, while in tissue engineering applications medium flow is required for efficient mass transport to the cells (e.g., ). The applied velocity of 18 μm/s would not induce negative effects on cell viability according to previous findings that the velocity of the smallest turbulent eddies of 0.4 cm/s was not damaging chondrocytes .…”

Engineering inkjet bioprinting processes toward translational therapies

“…Culture systems with poor medium transport properties would yield poorly developed tissues in vitro and necrotic tissue implants in vivo, rendering the therapy a failure (Fiedler et al, ). This is due to the fact that, when cells from the inner areas of scaffolds do not achieve their metabolic demand, starvation forces them to migrate to the surface or apoptosis (Forrestal, Klein, & Woodruff, ). This is particularly critical for oxygen availability, as its solubility in aqueous solutions is very low (Wu, Rostami, Cadavid Olaya, & Tzanakakis, ), and has been identified as the limiting nutrient in vivo and in vitro (Chow, Wenning, Miller, & Papoutsakis, ).…”

Cell proliferation and migration explain pore bridging dynamics in 3D printed scaffolds of different pore size

“…The last column lists the corresponding value of D λ estimated using Eq. (7). For clarity, Figure 5 only shows results with u c = 0.2 and u c = 0.5.…”

“…Although 3D scaffolds can approximate the form and function of natural extracellular matrices, many remain limited due to inconsistent scaffold architecture. Recent 3D printing (3DP) technologies which include melt electrowriting have enabled precise microscale manufacture of 3D culture scaffolds [5][6][7][8]. This consistency could allow a more complete control over cell behaviours, such as proliferation and migration.…”