In Vivo Screening Services – Animal Models -Molecular Biology Service Topics-Tekbiotech-Yeast and Phage Display CRO, Expert in Nano-body and Antibody Drug Development

In Vivo Screening Services – Animal Models

At TekBio, we not only focus on cutting-edge advancements in in vitro screening technologies but also dedicate ourselves to building a comprehensive R&D support ecosystem spanning from target discovery → in vitro screening → in vivo validation, thereby empowering our clients' projects to transition from the in vitro stage to the in vivo stage and from the conceptual phase to clinical development.

图1药物发现流程.png

Figure 1: Drug Discovery Workflow [2]

So, let's now answer why it is necessary to screen within live animals?

This involves the following factors.

1. absorb

How do drugs enter the bloodstream? Through oral administration, injection, or inhalation? It is essential to confirm that the drug can enter the bloodstream efficiently and stably.

The greatest challenge associated with oral administration is enabling the drug to penetrate the small intestinal cell membrane and enter the bloodstream; the drug's water solubility, lipid solubility, and molecular size all determine the rate and extent of absorption. Intravenous injection represents the most direct and rapid route of administration, offering a 100% bioavailability; it is generally used for emergency situations or for drugs requiring high absorption efficiency. Inhalation administration allows the drug to rapidly enter the bloodstream through the vast surface area of the alveoli; this route is suitable for asthma medications or general anesthetics.

2. distribution

After entering the bloodstream, drugs are transported throughout the body via systemic circulation; however, this distribution is not uniform. This raises a critical question: can the drugs that have entered the bloodstream precisely reach their target organs (lesions)?

In organs with rich blood supply—such as the heart, liver, kidneys, and brain—drugs typically reach these sites relatively quickly. However, due to the presence of the blood–brain barrier and placental barrier, many drugs intended for treating neurological disorders struggle to cross these barriers; therefore, whether a drug can penetrate the blood–brain barrier is a critical criterion during the screening process. In animal experiments, the ability to determine whether the drug has been administered at the correct site can be assessed by measuring its concentration at different anatomical locations.

3. supersession

Metabolic processes primarily occur in the liver; the human body treats most exogenous chemicals as "invaders" and activates a robust detoxification system to modify them – this process is known as metabolism. As a result, drugs may either lose their activity or become activated, or even give rise to toxic substances. By continuously monitoring changes in blood drug concentrations during in vivo pharmacokinetic studies, the metabolic rate (half-life) of a drug can be calculated, and any hepatic impairment can be detected, thereby enabling an assessment of its metabolic profile and safety profile.

4. drain

The primary route of excretion is through the kidneys; during drug screening, it is essential to determine the duration of drug retention in the body (half-life). If the half-life is too short, the therapeutic effect will be transient, necessitating multiple dosing per day, which may lead to poor patient compliance; if the half-life is too long, it may result in drug accumulation in the body, potentially causing adverse effects.

When a mature drug enters the body, it inevitably undergoes these four stages; however, these processes cannot be fully replicated in vitro. In vivo screening, on the other hand, allows for a comprehensive, one-stop evaluation of all these stages.

How is in vivo screening performed?

1. Disease model selection

Rodent model

Mouse models serve as the primary approach, as they enable efficient simulation of human physiology and disease states; moreover, gene editing technologies are well-established, supported by comprehensive phenotypic analysis systems, and allow for the transplantation of human tissues. However, these models are limited by high costs, lengthy development timelines, and ethical considerations.

Zebrafish model

Zebrafish are small in size, reproduce rapidly, and are low-cost; their genome shares approximately 70% homology with that of humans, making them well-suited for large-scale, rapid preliminary screening and toxicity testing. It is noteworthy that zebrafish embryos remain transparent during early development, allowing researchers to observe them in real time and dynamically under a microscope. However, zebrafish lack organs unique to mammals and cannot be used for complex behavioral assays.

Figure 2: Drug Development Process and Challenges [1]

2. Introduction of candidate drugs

Candidate compounds identified through preliminary in vitro screening will be administered to these disease model animals at precise doses and via specific administration routes.

3. Multi-dimensional Effect Evaluation

Through a series of complex and precise procedures—including behavioral observation, imaging examinations, biomarker detection, and histopathological analysis—the molecule that proves both effective and relatively safe in vivo will emerge from this process and qualify for advancement to the next research stage.

Tek Biotech(Tianjin) Co., Ltd. is a high-tech enterprise specializing in preclinical pharmacodynamic and safety evaluation. Leveraging its comprehensive animal experimentation platform and technical team, Tek Bio-Technology provides clients with one-stop, high-standard in vivo screening services that enable precise drug administration and dynamic monitoring; by integrating multi-dimensional assessment systems—including imaging, behavioral analysis, and molecular biology—the company facilitates full-process tracking of drugs within living organisms.

References

[1] Crouzier L,Richard EM,Sourbron J, et al. Use of Zebrafish Models to Boost Research in Rare Genetic Diseases. Int J Mol Sci. 2021;22 (24)

[2] Marei HE,Khan MUA,Hasan A. Potential use of iPSCs for disease modeling, drug screening, and cell-based therapy for Alzheimer's disease. Cell Mol Biol Lett. 2023;28 (1):98.

[3] Wenhao Wang, Xuan Gao,et al. Zebrafish as a vertebrate model for high-throughput drug toxicity screening: Mechanisms, novel techniques, and future perspectives.Journal of Pharmaceutical Analysis,Volume 15, Issue 9,2025,101195.

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