Just had my first #stemcell treatment done in Munich with Dr.Rembeck / Proffesor Alt for my ankle/knee …more to come ! — Boris Becker (@TheBorisBecker) May 6, 2016 We are seeing a flood of professional athletes getting stem cell treatments in the past few years. Just recently it was Ronaldo and now Boris Becker too. Before that Nadal had one. Gordie Howe. Bart Starr.