The present disclosure provides a method of storing stem cells while maintaining high viability at low temperatures in an unfrozen state. In one aspect, the present disclosure is a method for storing stem cells and provides the method including: 1) a step of providing a storage solution including a gelling agent at a temperature more than a gelling temperature in a non-gelled state and having a pH of about 5.0 to about 8.0; 2) a step of putting the stem cells into the storage solution and then lowering a temperature to the gelling temperature of the gelling agent; and 3) a step of storing the storage solution including the stem cells at a gel-state maintaining temperature of the gelling agent. In some embodiments, the gelling agent may include collagen, denatured collagen, collagen-like peptide, gelatin, or any combination thereof.

Methods and kits for sample preparation are provided, wherein a sample comprising at least one cell or tissue is contacted sequentially with a hydrophobic crosslinker, and then a hydrophilic crosslinker. The method prevents cell and tissue analytes from diffusing out of the at least one cell or tissue, such that the cell and tissue analytes can be analyzed and/or imaged.