We offer microinjection of purified DNA constructs for the production of transgenic mice. This includes injection of a single transgene construct (plasmid-based or BACs) that has been prepared by the investigator. A minimum of two transgenics or 20 live births or embryos, whichever comes first, is prepared for each set of injections charged to an investigator. Standard transgenic founders are established in either B6D2 hybrids or FVB/N inbreds, while injections can be done in less efficient strains, such as C57Bl/6J, as well. The cost of mice and health testing are additional and added at the time of billing.

Protocols for the purification of plasmid-based transgenes that are less than 20 kb, and for the purification of tail DNAs for genotyping of potential founders as follows:

Transgene Purification for Microinjection

Tail DNA Purification for Genotyping 

Recent advances in the field have allowed the CoRE to use CRISPR technology to do genome editing in vivo.  This approach allows the CoRE to create novel targeted genes (knock-outs, knock-ins, etc.) in as little as one to two months, compared with the generation of similar targeted models using ES cells which can take 6 to 12 months or more. The cost of mice and health testing are additional and added at the time of billing. 

Mouse lines can be imported into the Icahn School of Medicine at Mount Sinai by obtaining one to two males from a collaborator at another institution. These males are used to prepare sperm for in vitro fertilization (IVF) of wild-type mouse oocytes. The fertilized embryos are transferred to specific pathogen-free hosts to generate clean mice. The cost of mice and health testing are additional and added at the time of billing.

The CoRE recovers lines from which sperm have been frozen and stored at the Icahn School of Medicine at Mount Sinai. To minimize losses in the case of a freezer failure, cryopreserved sperm samples are maintained in two separate locations.

The CoRE also works with investigators to import lines of mice into Mount Sinai through live, early-stage embryos, frozen embryos, or frozen sperm. These methods can offer a relatively quick solution to importation of animals that avoids quarantine issues such as quarantine space, and the quarantine time itself. The cost of mice and health testing are additional and added at the time of billing.

The CoRE provides microinjection of selected embryonic stem (ES) cell clones into mouse blastocysts to establish chimeric mice to produce knockout mouse lines. Depending upon the goals of the study, live offspring, pre-implantation or mid-gestation embryos, can be provided. The cost of mice and health testing are additional and added at the time of billing.

The long-term storage of mouse sperm and/or embryos reduces the need for constant maintenance of lines not essential for current research needs, as well as providing a backup repository of important lines in case of environmental or weather-related crises. 

By transferring embryos to pathogen-free hosts, mouse lines infected with various mouse pathogens may be cleaned. This allows these lines to be shipped to collaborators at other institutions or to be moved into cleaner, barrier facilities at the Icahn School of Medicine at Mount Sinai. The cost of mice and health testing are an additional cost added at the time of billing. 

Cryopreserved sperm samples can be shipped from Mount Sinai to collaborators around the world. This service includes the preparation and loading of dry liquid nitrogen shippers with frozen sperm samples.

The CoRE can also provide mouse embryos at various preimplantation stages. The cost of mice is an additional cost and added at the time of billing.

The CoRE can produce embryonic stem cells from the blastocysts of existing mouse lines. This is a useful technique for laboratories that would like to generate their own embryonic stem cells for in vitro or in vivo studies.

The CoRE can use sub-cloning techniques to produce high-quality embryonic stem cells from lines which have lost their germline potential. This approach is beneficial in cases where embryonic stem cells fail to produce germline transmission due to changes in karyotype, etc.

New projects must be added to the schedule of the CoRE’s existing projects. Generally, a few weeks are needed from the time a request is received for mice to be ordered until delivery to the facility's animal housing room. In most cases, the facility can usually begin a project within two-three weeks of receiving a request and injection materials, but this is dependent on the existing schedule.

It typically takes several months from the time a request is received until founders are available for an investigator's use. Assuming a minimum of two weeks for ordering and receiving the mice needed, three weeks for gestation, three weeks for lactation, and two weeks for health testing post-weaning, it is usually a minimum of 10 weeks from request receipt to transfer of founders to an investigator. This may be lengthened by factors such as the need for repeat injections or problems with the quality of injection material.

No, the facility does not breed founders. There is insufficient space and resources for the facility to do so. If an investigator needs assistance with breeding of founders, they should contact the Rodent Colony Management Program.

No, the facility does not cryopreserve mouse embryos. Cryopreserving embryos is more complicated, as it usually requires female mice of a certain age (five to six weeks old) to be super ovulated and mated with males of the same line that are 3 to 10 months of age. For each attempt at embryo cryopreservation, at least 10 to 12 females (and an equal number of males for the mating) are required, and this is usually difficult to organize with the requesting lab.

The CoRE facility has successfully used males greater than 24 months of age to rescue mouse lines by IVF. This is not ideal, however, since as males age, they tend to have reduced or no sperm counts, which make IVF recovery less likely with age.