Investigating the Effects of Fertilized Egg Yolk Extract on Myoblast Proliferation and Differentiation

Abstract: Muscle disorders like sarcopenia are characterized by compromised skeletal muscle mass and function. This is caused by the failure of satellite cells or myoblasts to fuse together to form myofibers, or decreases in their number and function. Therefore, any analysis of interventions for muscle wasting should observe their effects at the cellular level. There are a number of commercially available nutritional products that claim to increase muscle mass and health. One potential supplement is fertilized chicken egg yolk; it is rich in vitamins, minerals, fats, amino acids, and proteins which can provide a sustained supply of nutrition to the myoblasts. As reversing the effects of sarcopenia involve muscle tissue growth, and tissue growth is a prime component of regenerative/tissue engineering, one could evaluate the effectiveness of nutritional supplements using regenerative/tissue engineering tools. In the present study, we evaluated the effect of different concentrations of fertilized chicken egg yolk extract on the viability, morphology, and myogenic gene expression of C2C12 myoblasts, common tools in regenerative/tissue engineering and regenerative medicine. Egg yolk (fertilized and unfertilized) extract in media enhanced the proliferation and differentiation of myoblasts in a dose-ependent manner as observed by increased cell viability, number of nuclei, number of myofibers, and mRNA expression of muscle-specific genes such as MyoD and myogenin. There was no significant difference in cellular metabolism/proliferation between myoblasts exposed to fertilized and unfertilized egg yolk, but there were differences in cellular morphology and cell fusion between the two groups at specific concentrations. Lay Summary: Muscle loss is frequently the result of aging or extreme sickness. While muscle loss and the effectiveness of any treatment is usually measured by physicians using visual observations of muscle tone or changes in weight, as this problem occurs at the cellular level, the effectiveness of any intervention should also be examined at the cellular level. Nutritional supplements are frequently used to combat muscle loss. One potential supplement is fertilized chicken egg yolk; it is rich in vitamins, minerals, fats, amino acids, and proteins which can provide a sustained supply of nutrition to muscle cells (myoblasts). In manuscript, we describe a study that tested the effectiveness of fertilized chicken egg as a way of combating muscle loss. We exposed myoblasts to different concentrations of fertilized egg yolk and looked at their effects on the behavior of the myoblasts. Exposure to egg yolk (fertilized and unfertilized) increased the number of cells and caused the cells to produce factors associated with muscle development in a dose-dependent manner. Exposure to fertilized egg yolk led to a more muscle-like shape in myoblasts (they fused together to form the multinucleated structures seen in muscle) compared to unfertilized egg yolk at specific concentrations.