Gibberellic acid induces α-amylase expression in adipose-derived stem cells

Salivary α-amylase is the most important enzyme for oral digestion of dietary starch. Therefore, regeneration of the salivary glands via a tissue engineering approach is clearly required for patients with salivary gland dysfunction. Early during seed germination, the embryo synthesizes gibberellic acid (GA3), a plant hormone that activates the synthesis and secretion of α-amylase. The purpose of this study was to explore an approach for differentiation of stem cells into salivary glands using GA3. We isolated adipose-derived stem cells (ASCs), which are positive for mesenchymal stem cell markers (CD73, CD90 and CD105) and possess pluripotency to osteoblasts, adipocytes and neural cells, from human buccal fat pads, which are a readily available source for dentists and oral surgeons. In addition, we investigated the cytotoxicity of GA3 for human ASCs. GA3 neither affects cell morphology nor cell viability in a dose- or time-dependent manner. ASCs were incubated with GA3 to assess mRNA and protein expression of α-amylase by reverse transcriptase-polymerase chain reaction and western blot analyses. α-amylase mRNA expression on 21 days after treatment with GA3 (1 mM) was seven times greater than that in resting condition (Day 0). While we did not detect α-amylase bands on Day 0, α-amylase protein was detectable 7 days after treatment with GA3, reaching a maximal level on Day 21. Our results indicated that GA3 can increase cellular α-amylase expression and that our induction method would be useful for therapeutic application for salivary gland regeneration.