Abstract: Provided is a novel structure containing mesenchymal stem cells that can be used in various applications. A hydrogel fiber (10) comprises a hydrogel (14) that contains mesenchymal stem cells.

Abstract: A scaffold for culturing a cell comprises: a hydrogel; and a plasma-derived or platelet-derived component or a fibrin-containing material adhered to the hydrogel.

Abstract: A cell fiber production system comprises: a first flow path through which a first fluid containing a cell flows; a second flow path for allowing a second fluid for preparing a hydrogel to converge around the first fluid in the first flow path; and an ejection port through which at least the first fluid and the second fluid are discharged together. The cell fiber production system is constructed that, at a start stage of production of a cell fiber, the first fluid is delivered after the second fluid reaches at least a convergence point between the first flow path and the second flow path.