Umbilical cord mesenchymal stem cells for COVID‐19 acute respiratory distress syndrome: A double‐blind, phase 1/2a, randomized controlled trial oleh Giacomo Lanzoni, Elina Linetsky, Diego Correa, Shari Messinger Cayetano, Roger A. Alvarez, Dimitrios Kouroupis, Ana Alvarez Gil, Raffaella Poggioli, Phillip Ruiz, Antonio C. Marttos, Khemraj Hirani, Crystal A. Bell, Halina Kusack, Lisa Rafkin, David Baidal, Andrew Pastewski, Kunal Gawri, Clarissa Leñero, Alejandro M. A. Mantero, Sarah W. Metalonis, Xiaojing Wang, Luis Roque, Burlett Masters, Norma S. Kenyon, Enrique Ginzburg, Xiumin Xu, Jianming Tan, Arnold I. Caplan, Marilyn K. Glassberg, Rodolfo Alejandro, Camillo Ricordi