Accurate Implantation of Osteosarcoma Cells Intratibially

DATE: April 2021
Ann & Robert H. Lurie Children's Hospital of Chicago | Dept. of Pediatric Hematology and Oncology
Casey Mehrhoff, D.O. | Clinical Pediatric Oncology Fellow

Through use with the Hamilton needle and syringe, pediatric osteosarcoma cells will be injected directly into the tibia of mice. Through this method, orthotopic patient derived xenograft models of pediatric osteosarcoma will be created, and later treated with novel therapies. The Hamilton syringe is necessary for safely injecting osteosarcoma cells intratibially. The method involves flexing the hindleg of the mouse, identifying the superior edge of the tibia, and drilling a hole with a 27 gauge needle by gently applying pressure in a twisting motion. Once the 27 gauge needle has passed into the bone marrow of the mice, the needle is removed. After identification of the created hold, the Hamilton needle and syringe will then be used to safely and precisely inject the proper volume of osteosarcoma tumor cells intratibially. If air bubbles or too large of a volume is injected, this can risk air embolization to the mouse brain, ultimately leading to mouse fatalities.

Through accurate implantation of osteosarcoma cells, the Hamilton syringe will allow for precise monitoring of tumor by allowing for a standard growth curve to be followed. Attempts have been made to replicate accurate tumor implantation with use of smaller needles/syringes, such as with the use of a TB syringe. However, accurate volumes cannot be injected. Therefore, the number of osteosarcoma tumor cells injected into each mouse is variable. This technique will allow for more precise tumor injections, which will increase the rates of success for all six lab members (two who are post docs, and one who is a clinical oncology fellow).

I have populated five osteosarcoma cell lines which can be used for intratibial implantation into murine models, and each cell line has over one trillion cells available. In addition to this, through a research and clinical connection with Ann & Robert H. Lurie Children's Hospital of Chicago, patients are consented at the time of diagnosis to provide tissue tumor samples for research. As a clinical pediatric oncology fellow who also works in a lab, I have the opportunity to work closely with pediatric patients and other physicians, and am able to personally consent patients/their parents when appropriate for research studies in lab. Since I started injecting mice with osteosarcoma just one month ago, I have been able to inject four patient tumor samples into mice and two cell lines. This number will only continue to grow as the process for collecting patient tumor samples continues to develop and prosper. Additionally, I have been given two osteosarcoma PDOX models from St. Jude Children's Research Hospital which should be available for implantation in one week. Therefore, I have many osteosarcoma tumor models available for use. Due to the precious nature of these cells, specifically those that come from patients, there is no room for error or "waste", which is why the Hamilton syringe would be so beneficial and allow for the utmost accuracy.