Evaluation of royal jelly as an alternative to fetal bovine serum in cell culture using cell proliferation assays and live cell imaging

Abstract

Background: Royal jelly is a nutritious substance produced by the young nurse bees and contains significant amounts of proteins which are important for cell growth and proliferation. The aim of this study was to evaluate the effect of royal jelly as an alternative to fetal bovine serum (FBS) in cell culture using cell proliferation assays and live cell imaging.

Materials and methods: MRC-5 cells were treated with various concentrations of royal jelly extract in MTT assay. The control groups were comprised of Alpha-Minimal Essential Medium (α-MEM) alone and α-MEM with 10% FBS. Subsequently, the cell proliferation was studied for 10 days using Alamar Blue assay and live cell imaging from 48 to 72 h. The population doubling time (PDT) was determined using trypan blue assay after live cell imaging.

Results: In MTT assay, 0.156 and 0.078 mg/ml of royal jelly produced higher cell viability compared to positive control group but were not significantly different (P > 0.05). In the Alamar Blue assay, 0.156 and 0.078 mg/ml of royal jelly produced greater percentage of reduction at day 3 even though no significant difference was found (P > 0.05). Based on live cell imaging, the PDT for positive, negative, 0.156 and 0.078 mg/ml of royal jelly groups were 29.09, 62.50, 41.67 and 41.67 h respectively. No significant difference was found in the PDT between all the groups (P > 0.05).

Conclusion: Royal jelly does not exhibit similar ability like FBS to facilitate cell growth under the present test conditions.

Keywords: Royal jelly; cell division; live cell imaging; proliferation.

Figure 1

MTT assay of royal jelly on human lung fibroblast cell line (MRC-5)

Figure 2

Cellular morphology of MRC-5 cells treated with (a) 0.156 mg/ml royal jelly; (b) 0.078 mg/ml royal jelly, and (c) Positive control (α MEM + 10% FBS)

Figure 3

Standard curve of MRC-5 cells for Alamar Blue assay

Figure 4

Results of Alamar Blue test on MRC-5 cells treated with 0.156 and 0.078 mg/ml of royal jelly (RJ), positive and negative control

Figure 5

Representative images of MRC-5 cells treated with royal jelly through live cell imaging. a negative control (0 h); b negative control (24 h); c positive control (0 h); d positive control (24 h); e 0.156 mg/ml of royal jelly (0 h); f 0.156 mg/ml of royal jelly (24 h); g 0.078 mg/ml of royal jelly (0 h) and h 0.078 mg/ml of royal jelly (24 h) (Scale bar: 50 µm)

Figure 6

Cell division process of MRC-5 cells (negative control). a After 7.30 h (single cell); b After 10.30 h; c After 12.30 h; d After 13.00 h; e After 13.30 h; f After 14.00 h; g After 14.30 h and h After 15.00 h (two daughter cells). Arrow denotes the individual cells.