Effect of natural honey treatment and external stretching on kinematics of cell migration during gap closure

Abstract

Wound healing is a complex natural response to tissue injury intended to restore the integrity and function of the tissue at the wounded site. The wound healing process occurs naturally under physical/mechanical forces, e.g., local stretching, and in many cases, benefits from application of applied remedies. Identification of potentially effective compounds requires specialized approaches to determine their effects on different cell types. However, working in vivo has quantification limits and ethical concerns arise. This is especially true for natural origin compounds, such as plant extracts, honey, and larvae, which have a complex composition and determining their clinical efficacy is challenging. Thus, in vitro gap closure assays can be used to evaluate the effects of natural treatments and external strains on migration associated with gap closure. Here, we evaluate the changes in cell migration during gap closure in vitro, following treatment with honey and/or under applied external strains. We generated monolayers of NIH3T3 mouse fibroblasts and induced a small gap (wound) at their center. Using custom image processing modules, we measured the kinematics of the gap closure, focusing on times of initiation and rates of migration. We evaluated the effects of different concentrations of a well-known natural wound-care agent, i.e., honey. Honey has been used in skin wound care for many years due to its anti-inflammatory, antimicrobial, and cell-stimulating properties. Using our assay we are able to show the direct effects of honey on the migratory capabilities of the cells and the kinematics of gap closure. In addition, we evaluate the effects of externally applied stretching, with and without the addition of natural remedies, on the gap closure process. For this, we grow the cell monolayer on an elastic, stretchable membrane, which is then stretched in varying levels using a 3-D printed cell stretching apparatus. We evaluated the effects on gap closure kinematics of different levels of externally applied strains, showing that low (3%) strains may accelerate gap closure, while higher (6%) strain may not be as efficient, relative to unstretched control. Thus, combining external deformation with various treatments can enhance the rate of migration and thus shorten the time required for wound healing.