A histological study of mouse tissues and water loss following lyophilization

Lyophilization is a practical method for product storage and transportation; it commonly is used in the food and pharmaceutical industries. Lyophilization also is used for preserving biological samples such as serum, plasma and animal tissues. We found that lyophilization does not affect the stability of RNAs and proteins in tissue samples. To investigate histological characteristics, we prepared lyophilized tissues for paraffin sectioning and hematoxylin and eosin (H & E) staining. We also measured water loss from organs during lyophilization. We used immunohistochemistry of frozen brain sections to identify potential protective effects of three concentrations of sucrose, glucose and trehalose against the effects of lyophilization. H & E staining revealed vacuoles in heart, lung, liver, kidney, spleen and brain after lyophilization without pretreatments, especially heart and kidney. We found that 10% solutions of sucrose, glucose and trehalose helped preserve tissue morphology. Immunohistochemistry of frozen brain tissue showed that 10% glucose and 30% sucrose preserved cellular characteristics and immunogenicity following lyophilization. Lyophilization removed > 70% of the water from organs, and lyophilized tissues without protectants were not suitable for histological study. Overall, we found that 10% glucose helped preserve both optimal tissue morphology and immunogenicity of freeze-dried tissue.