Intraoperative stem cell therapy. (a) The intraoperative cell therapy process typically includes tissue harvesting and processing to obtain the desired cell product, and an intraoperative cell delivery strategy that depends on the clinical application. (b) The intraoperative cell therapy process starts with autologous tissue harvesting. Tissues, including peripheral blood, adipose tissue, and bone marrow, can be used as sources of stem cells (green box). The tissue can then be processed using multiple methods (blue box) to obtain the desired cell product (orange box). The stem cell therapy can be applied as an adjunctive treatment in combination with surgery or an interventional treatment (yellow boxes). Figure was produced using Servier Medical Art (http://www.servier.com/servier-medical-art).

Selective cell retention. After harvesting, (a) the bone marrow is drawn through (b) an implantable graft matrix. This process facilitates matrix exposure to a high volume of bone marrow in a short time. The process is repeated until graft saturation is achieved. Several porous materials can be used as a graft matrix, e.g., demineralized bone matrix, cancellous bone chips, hydroxyapatite, and β-tricalcium phosphate. A higher fraction of mesenchymal progenitor cells are retained within the graft, whereas the retention of hematopoietic cells is significantly lower (c). After enrichment the graft is ready for implantation, although postprocessing procedures such as addition of whole bone marrow or platelet-rich plasma can be performed to improve graft handling properties and to improve the therapeutic potential of the graft. Figure was produced using Servier Medical Art (http://www.servier.com/servier-medical-art).