The number of voluntary donors to China's bone marrow databank reached 1 million on Friday, and is expected to be doubled in five years, the Red Cross Society of China (RCSC) said Tuesday. 'The result has been achieved by concerted efforts from society and will raise hopes for patients looking outside the family to match of hematopoietic stem cells (HSCs), said Jiang Yiman, vice president of the RCSC. Hematopoietic stem cells are multipotent stem cells that give rise to all blood cell types. They can be found in the bone marrow of adults. Patients suffering leukemia in China are increasing by 40,000 a year, and there are about 1 million patients waiting for transplants of HSCs. China's bone marrow databank provides a matching and retrieving service for more than 14,000 patients. It has also made 1,300 donations to overseas patients. In addition, the RCSC had set up a bone marrow databank fund to boost the development of HSC transplantation and offer greater assistance to poor leukemia patients. 