Optimized protocols for sperm cryopreservation and in vitro fertilization in the rat

Area of Science:

• Animal Science
• Reproductive Biology
• Biotechnology

Background:

• Laboratory rats are crucial models in biomedical research, with increasing use of genetically modified strains.
• Genome editing technologies have heightened the need for efficient methods to preserve and produce rat genetic resources.
• Sperm cryopreservation offers a robust strategy for archiving genetic material and reducing animal numbers in colony management.

Purpose of the Study:

• To describe an improved in vitro fertilization protocol to increase the fertilization rate of cryopreserved rat sperm.
• To provide a streamlined process for generating live rat pups from cryopreserved sperm.

Main Methods:

• Optimization of in vitro fertilization by treating frozen-thawed rat sperm with a high concentration of bovine serum albumin (40 mg/ml).
• Implementation of a three-step protocol: sperm preparation, in vitro fertilization, and embryo transfer.
• Validation across major rat strains.

Main Results:

• The optimized protocol significantly enhances the in vitro fertilization rate of cryopreserved rat sperm.
• Live rat pups can be produced from cryopreserved sperm within approximately one month.
• The protocol is adaptable for researchers with varying levels of reproductive engineering experience.

Conclusions:

• This enhanced sperm cryopreservation and in vitro fertilization protocol provides an efficient system for archiving and producing genetically modified rats.
• The improved technique supports the global transgenic research community by ensuring reliable access to valuable rat models.
• This method facilitates the long-term preservation of rat genetic resources, reducing the need for extensive animal colonies.