Service Overview
CLEA Japan undertook a contract research project to establish a rat tumor-bearing model using B16F10 melanoma cells for oncology research, specifically an intracranial implantation model.
Healthy and genetically uniform rats produced in-house by CLEA Japan (e.g., Wistar, Sprague Dawley) were used. All procedures—from cell preparation and stereotaxic intracranial implantation to post-operative observation and delivery—were conducted by experienced technical staff.
Under strict management in compliance with animal welfare standards and internal regulations, tumor-bearing models were established with high reproducibility, providing robust support for tumor biology research and pharmacological efficacy studies.
Workflow of the Contract Research Process
①Initial Consultation and Requirement Assessment
・Type of cells to be implanted and stereotaxic coordinates・Number of animals, age, sex, observation period, and shipment schedule
②Quotation and Formal Contract Agreement
③Preparation of Implantation Cells (Example)
・Cell preparation using RPMI-1640 medium, Penicillin–Streptomycin, Trypsin-EDTA, etc.・Adjustment to the specified cell concentration (e.g., 1.0 × 10⁵ cells / 3 µL)
④Intracranial Implantation into Rats (Stereotaxic Surgery)
・Performed under combined anesthesia (three-agent cocktail with isoflurane as an auxiliary anesthetic)・Implantation site determined based on coordinates from the reference point (Bregma), e.g., AP 0.5 mm, ML 2.0 mm, DV 3.5 mm
・A burr hole is drilled in the skull, and a microsyringe is inserted at the designated coordinates
・Cells are implanted at the specified volume; post-operative analgesia and care are provided
⑤Observation, Body Weight Measurement, and General Health Monitoring
・Daily clinical observation・Body weight measurements once or twice per week
・Detection and documentation of abnormal findings
⑥Shipment and Delivery
・Depending on the contract, either live model rats are shipped or organs/tissues are collected and supplied
Our Strengths：
・ Breeder-Level SPF Environment
All surgically treated animals are housed and managed under the same strict SPF conditions as CLEA’s breeding colonies throughout the entire process, from surgery to delivery. This consistently controlled environment ensures extremely high reproducibility of experimental data and has earned strong trust from researchers.
・Highly Reproducible Techniques by Experienced Personnel
Our technical staff possess extensive experience in:
・Stereotaxic intracranial implantation
・Cell preparation
・Post-operative observation
Their advanced skills in coordinate setting and surgical procedures enable the provision of stable tumor models with minimal inter-animal variability.
・Safe and Ethical Operations Based on Animal Welfare and Internal Regulations
All procedures are conducted in accordance with experimental protocols reviewed and approved by the Institutional Animal Care and Use Committee. Appropriate anesthesia, post-operative care, monitoring, and humane euthanasia are ensured, providing a reliable framework for safe outsourcing.
FAQ
Q: What types of tumor-bearing models can you establish?
A: In addition to the intracranial implantation model described here, we also support subcutaneous and intravenous implantation models.
Q: What animals are used in these studies?
A: SPF rats produced by CLEA Japan (e.g., Wistar, Sprague Dawley) are used.
Q: How is intracranial implantation performed?
A: Under combined anesthesia (with isoflurane as an auxiliary anesthetic), cells are implanted using a stereotaxic apparatus according to coordinates based on the Bregma reference point. Dosage and coordinates can be adjusted upon request.
Q: Can observational data be provided?
A: Yes. Data such as body weight, clinical observations, and abnormal findings can be provided according to your requirements.
Recommended for the Following Needs
- Outsourcing brain tumor model establishment to improve procedural reproducibility
- Requesting highly technical models such as intracranial implantation models
- Standardizing tumor-bearing models to reduce variability in pharmacological evaluations
- Conducting studies using healthy rats with well-documented background data provided by a breeder
Interview with the Technical Staff
Q1. What types of researchers typically inquire about this tumor model?
Most inquiries regarding this intracranial tumor model came from university researchers. Technically, intracranial cell implantation is quite similar to procedures used for Parkinson’s disease models—the main difference being whether reagents or live cells are injected.
We had experience with approximately three to four Parkinson’s disease model studies per year, as well as routine subcutaneous implantation of tumor-bearing mice. However, the request to implant melanoma cells into the brain was initially surprising, as subcutaneous models are more commonly used. It was interesting to realize that such alternative approaches were being explored.
Given our prior experience, we felt confident that the procedure was technically feasible, and personally, I found the challenge quite intriguing.
Q2. How many tumor model projects do you handle annually?
For intracranial administrations, we handle approximately three to four Parkinson’s disease model projects per year. In addition, we routinely perform a wide range of surgical animal procedures, so we are highly familiar with these techniques.
With two skilled technicians, it is feasible to process approximately ten animals per day. This type of work is rewarding for those who value precision and the satisfaction of producing reliable results.
Q3. What are the most critical points to consider when establishing tumor models?
Cell handling is the most critical aspect. When Matrigel is used, even slight temperature increases can cause gelation, so cells must be maintained under cooled conditions at all times.
Therefore, not only the cells but also syringes and auxiliary instruments, such as medical freezing sprays, are pre-cooled. This is a tumor-model-specific consideration that is not required for reagent-based models like Parkinson’s disease models.
Another crucial factor is accurate identification of the Bregma. In stereotaxic surgery, reproducibility is highly dependent on ensuring that all team members share the same recognition of the Bregma location.
Initially, two experienced technicians handled the procedures, but after adding two new members, the team now maintains a strong consensus and consistency.
Additionally, assessment of individual variability is important in tumor models. Tumor engraftment, growth, and body weight loss inevitably show some variation.
For example:
- Mild body weight loss is often a sign of successful engraftment
- Excessive weight loss may indicate failure
- Minimal change may also suggest poor engraftment
In this way, we make a comprehensive assessment by monitoring not only body weight trends but also behavioral changes and physical appearance, such as subtle variations in head shape.
Furthermore, minute details—such as the speed of syringe withdrawal, the handling of the drill, and the treatment of the skull surface—are where the level of surgical proficiency truly shows.
Q4. What are the advantages of outsourcing to CLEA Japan?
The greatest advantage is access to technicians highly experienced in intracranial administration and engraftment procedures. In particular, the shared and consistent recognition of the Bregma within the team is a major strength in terms of reproducibility.
High reproducibility inevitably requires extensive experience and technical proficiency, and we appreciate that this aspect is valued by our clients.
In addition, close collaboration with our in-house tumor model team allows smooth information sharing between cell culture and observation teams.
Q5. Are there additional optional services available?
We offer flexible support for animals handled by CLEA Japan. For example, instead of proceeding directly to a full-scale study, a preliminary pilot study can be conducted with a small number of animals to confirm engraftment before initiating the main study.
In addition to model establishment and delivery, we can also support subsequent dosing studies and organ/tissue collection. By understanding how much of the process clients wish to outsource, we aim to propose workflows that ensure smooth and efficient study progression.
