Injection of ES cells into blastocysts

Introduction and considerations

Homologous recombination in ES cells is no longer on the list of services provided by NTS. Such projects previously conducted in ES cells can now more conveniently be achieved with CRISPR-based approaches. However, NTS may assist with injection of ES cells into blastocysts if the customer has ES cells available. The technique is time demanding and performed with a relative high risk, since NTS will have no knowledge of the quality of the ES cells in question.

ES cells correctly targeted with homologous recombination may be injected into mouse embryos (blastocyst stage) where some of the developing tissue/organs will be derived from the injected ES-cells. Only undifferentiated injected ES cells will contribute to the germ line. The use of undifferentiated cells is therefore crucial to be able to generate offspring that carries the mutated ES cells (chimera). Experience in culturing of ES cells is therefore a prerequisite for a successful project.

Description of the service

  • ES cells are purified on the day of injection, injected into blastocysts, followed by implantation into pseudopregnant foster mothers.
  • Provided that the ES cells are undifferentiated, chimeric mice made up by cells originating from the blastocyst and from the injected ES cells are born approximately 17 days after the transfer.
  • The research group (customer) can receive the chimeras for breeding at an age of approximately 3-6 weeks.

Requirements and time-frame

  • The customer may deliver ES cells for injection (preferred by the Centre). The customer can only deliver ES cells at planned injection days after agreement and prior coordination with NTS.
  • Alternatively, NTS can culture and prepare ES cells for injection at additional cost.
  • NTS will superovulate donor females to produce blastocysts.
  • Blastocysts are collected from female mice 3.5 dpc (days post coitum). Only well-expanded blastocysts are selected for injection of ES cells.
  • Following injection, blastocysts are transferred into the uteri of pseudopregnant foster mothers.
  • Chimeric mice made up by cells originating from the blastocyst and from the injected ES cells are born approximately 17 days after transfer.
  • Project lasts typically for 10-15 weeks.

Technical service performed by NTS

  • NTS is responsible for the animal procedure permit (FOTS application).
  • Planning and coordination of the project.
  • Superovulation of donor females, mating overnight, dissection of oviducts and collection of embryos at 3.5 dpc.
  • Injection of ES cells into blastocysts.
  • Implantation of blastocyst into pseudopregnant foster mothers.
  • Separation of offspring and identification of chimeras.

Costs cover the following

  • Purchase and transport of donor females from vendors.
  • Housing of vasectomized males and foster mothers.
  • Housing of males for mating with donor females (for 4 weeks).
  • Up to four rounds of injection.
  • Confirmed birth of 30 offspring.
  • Housing of offspring until 6 weeks of age.

Service Fees

Estimated costs for the above service can be found on our Service Fees page.

Published Feb. 10, 2017 2:05 PM - Last modified Mar. 27, 2023 10:44 AM