The invention is directed to a method of freezing stem cells comprising introducing the HSCs into a cell culture medium that has been conditioned with Wharton's Jelly mesenchymal stem cells (WJSCs), thereby producing a stem cell culture, and slowly freezing the stem cell culture. In other aspects, the invention is directed to compositions comprising stem cells produced by the methods provided herein. In yet other aspects, the invention is directed to pharmaceutical compositions comprising the stem cells produced by the methods provided herein.