Influence of Calcium Ions on Cell Survival and Proliferation in the Context of an Alginate Hydrogel

Abstract

One goal of biofabrication is to incorporate living cells into artificial scaffolds in order to repair damaged tissues or organs. Although there are many studies on various biofabrication techniques, the maintenance of cell viability during the biofabrication process and cell proliferation after the process is still a challenging issue. Construction of scaffolds using hydrogels composed of natural materials can avoid exposure of cells to harsh chemicals or temperature extremes but can still entail exposure to nonphysiological conditions, causing cell damage or even death. This paper presents an experimental investigation into the influence on Schwann cell survival and proliferation of calcium used for ionic crosslinking of alginate hydrogel during the biofabrication process. The experimental results obtained show the viability and proliferation capacity of cells, either suspended in cell culture medium or encapsulated in hydrogel, and vary with the calcium concentration and the time period of cells exposed to the calcium environment. The experimental results also show the alginate concentration and cell density, that have profound influence on cell survival and proliferation, and solution viscosity as well. This study suggests the incorporation of living cells in calcium-crosslinked hydrogel in the biofabrication process can be regulated for controlled cell survival and proliferation.

Influence of crosslinking on the mechanical behavior of 3D printed alginate scaffolds: Experimental and numerical approaches

“…Extrusion-based techniques are widely used to print large tissue scaffolds with cells and in such a system, biopolymers dispensed simultaneously from a 3D biofabrication system (Cao et al, 2012;Naghieh et al, 2018) and provide custom-made scaffolds using imaging technology (Naghieh et al, 2016a). It has also been combined with other techniques like electrospinning to come up with newly developed scaffolds (Naghieh et al, 2017a(Naghieh et al, , 2017b.…”

“…Among various divalent ions, Ca 2+ ions facilitate superb printability for alginate precursors while maintaining reasonable cell viability (Swioklo et al, 2016). Mechanically stable alginate scaffolds can be successfully fabricated using CaCl2 solution at higher concentrations (You et al, 2016a), but the incorporated cells can be adversely affected (Cao et al, 2012). Therefore, extruding the alginate precursor into a lower concentration CaCl2 solution has been recommended to limit effects on cell viability (Tabriz et al, 2015).…”

“…Therefore, extruding the alginate precursor into a lower concentration CaCl2 solution has been recommended to limit effects on cell viability (Tabriz et al, 2015). Cellincorporated scaffolds should also be crosslinked immediately after printing to prevent significant decreases in cell viability (Cao et al, 2012). If the alginate precursor is extruded in a constant, low-concentration, and small volume of CaCl2 solution, the number of available Ca 2+ ions in the media might decline significantly with the progression of scaffold height; this, in turn, might affect the mechanical stability of the extruded hydrogel.…”

“…Similar to concentration, crosslinking time in Ca 2+ ions affects the viability of incorporated cells (Cao et al, 2012). In an extrusion-based system, the CaCl2 solution is often aspirated upon biofabrication without allowing sufficient time for the alginate scaffolds to achieve equilibrium with the Ca 2+ ions.…”

“…While some studies have focused on the concentration of crosslinker (Cao et al, 2012), here we exclusively concentrate on the effect of crosslinking time and volume for a fixed concentration of the crosslinking solution. The effect of these factors on the mechanical characteristics of the bioplotted scaffolds was investigated using experimental and numerical approaches.…”