Этот код может помочь вам ..
wBook = _excel.Workbooks.Add()
wSheet = wBook.ActiveSheet()
wSheet.Range(wSheet.Cells(vRow, vColNature), wSheet.Cells(vRow, vColMAX)).Merge()
wSheet.Range(wSheet.Cells(vRow, vColNature), wSheet.Cells(vRow, vColMAX)).WrapText = True
wSheet.Range(wSheet.Cells(vRow, vColNature), wSheet.Cells(vRow, vColMAX)).Font.Bold = True
wSheet.Range(wSheet.Cells(vRow, vColNature), wSheet.Cells(vRow, vColMAX)).Borders.LineStyle = 1
wSheet.Range(wSheet.Cells(vRow, vColNature), wSheet.Cells(vRow, vColMAX)).HorizontalAlignment = Excel.Constants.xlCenter