Effects of in vitro maturation on oocyte gene expression

In vitro oocyte maturation (IVM) holds great promise as a tool for enhancing clinical treatment of infertility, enhancing availability of non human primates for development of disease models, and facilitating endangered species preservation. However, IVM outcomes have remained significantly below success rates obtained using in vivo matured (VVM) oocytes from humans and non human primates. A cDNA array based analysis is presented, comparing the transcriptomes of VVM oocytes with IVM oocytes. We observe a small set of just 59 mRNAs that are differentially expressed between the two cell types. These mRNAs are related to cellular homeostasis, cell-cell interactions including growth factor and hormone stimulation and cell adhesion, and other functions such as mRNA stability and translation. Additionally, we observe in IVM oocytes overexpression of PLAGL1 and MEST, two maternally imprinted genes, indicating a possible interruption or loss of correct epigenetic programming. These results indicate that, under certain IVM conditions, oocytes that are molecularly highly similar to VVM oocytes can be obtained, however the interruption of normal oocyte-somatic cell interactions during the final hours of oocyte maturation may preclude the establishment of full developmental competence. Keywords: oocyte maturation Comparison of in vitro matured MII-stage oocytes (4 biological replicates) with in vivo matured MII-stage oocytes (4 biological replicates)