Abstract
            Background: Production of the recombinant proteins in mammalian cells is an important issue with  a bio-therapeutic purpose. Numerous efforts have been focused on the improvement of the yields of  recombinant proteins, which include optimization of conventional biological processes, selection of  appropriate signal peptides, codon optimization, and re-engineering of cells to produce more proteins.  Stem cell factor (SCF) is a blood cytokine which activates the c-Kit receptor. This factor is crucial not  only for the differentiation of hematopoietic progenitor cells but also for the survival, proliferation, and  differentiation of mast cells. Recently, its therapeutic role in several diseases such as Alzheimer’s and  myocardial infarction has been investigated. Therefore, the aim of this study was to design a secretory  recombinant human SCF with the maximal yield in an appropriate mammalian host cell as Chinese  hamster ovary (CHO) cells using the computational studies.  
  Methods: As the first step, computational simulation studies were carried out to design the appropriate  signal peptide for the human SCF protein. Codon optimized coding sequence of hSCF was transferred  into a eukaryotic expression vector (pBudCE4.1). Recombinant vector (pBudCE4.1/SCF) was transfected  into CHO cells and the stably transformed cells were screened and isolated. Subsequently, the expression  of SCF was defined by reverse transcription polymerase chain reaction (RT-qPCR) in stably transformed  cells.  
  Results: Our bioinformatics studies indicated that Azurocidin signal peptide could be a suitable signal  peptide for the production of SCF proteins in the CHO cells. Accordingly, computational studies revealed  that the presence of 6×His-tag did not have a significant impact on the three-dimensional structure of the  protein. Furthermore, the expression of hSCF was significant in the stable CHO cells.  
  Conclusion: The use of this approach may, therefore, lead to the production of highly efficient recombinant  hSCF, which would be feasible for the mass production of this factor for therapeutic purposes.