Abstract: A cell population comprises a large number of cell aggregations and a hydrogel encapsulating the large number of cell aggregations. A coefficient of variation obtained by dividing a standard deviation of sizes of the large number of cell aggregations by a mean value of the sizes of the large number of cell masses is 0.50 or less. Alternatively and/or in addition there to, a coefficient of variation obtained by dividing a standard deviation of aspect ratios of shapes of the large number of cell aggregations by a mean value of the aspect ratios of the shapes of the large number of cell aggregations is 0.30 or less.

Abstract: Provided is a structure with which a lung progenitor cells can proliferate while retaining an ability to differentiate into an alveolar epithelial cell and an airway epithelial cell. A structure of the present invention includes a core portion that includes a cell population, and an outer shell portion that covers at least a part of the core portion and contains a hydrogel. The structure has a storage elastic modulus of 150 Pa or more and/or the hydrogel contains alginic acid. The cell population contains an alveolar epithelial cell, an airway epithelial cell, and/or a progenitor cell thereof.

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.