Applications of a new In vivo tumor spheroid based shell-less chorioallantoic membrane 3-D model in bioengineering research

Abstract

The chicken chorioallantoic membrane (CAM) is a classical in vivo biological model in studies of angiogenesis. Combined with the right tumor system and experimental configuration this classical model can offer new approaches to investigating tumor processes. The increase in development of biotechnological devices for cancer diagnosis and treatment, calls for more sophisticated tumor models that can easily adapt to the technology, and provide a more accurate, stable and consistent platform for rapid quantitative and qualitative analysis. As we discuss a variety of applications of this novel in vivo tumor spheroid based shell-less CAM model in biomedical engineering research, we will show that it is extremely versatile and easily adaptable to an array of biomedical applications. The model is particularly useful in quantitative studies of the progression of avascular tumors into vascularized tumors in the CAM. Its environment is more stable, flat and has a large working area and wider field of view excellent for imaging and longitudinal studies. Finally, rapid data acquisition, screening and validation of biomedical devices and therapeutics are possible with the short experimental window.

Figure 1

H&E histological section of a 1 mm diameter ACBT glioblastoma spheroid embedded in CAM. Grey area is the CAM; center region in purple denotes the tumor spheroid. Dark purple regions along the top membrane denote tumor cells invading regions of the CAM; (a) Top view of tumor spheroid and CAM interface of the formalin fixed spheroid inside CAM (mesoderm) after removal from the chicken and embryo prior to histological processing; (b) Tumor microvasculature as a result of angiogenesis (1,2,3).

Figure 2

ALA mediated Photodynamic Therapy (PDT) in vascularized tumor spheroids implanted on the CAM of a chicken embryo. (a) Normal vascularized ACBT glioma spheroid pre-PDT; (b) Vascularized ACBT glioma spheroid post-PDT.

Figure 3

(a) 3-D Optical Coherence Tomography (OCT) and (c) Optical Doppler Tomography (ODT) imaging of CAM-spheroid section of a live chicken embryo (Image Acquisition Time ~2 min). (b) This figure shows real time ODT imaging of blood flow in a major blood vessel in the CAM next to the spheroid. The different colors represent the velocity of blood flow. Black color represents zero velocity and red color represents maximum velocity. Velocity increases from black, green, yellow to red.

Figure 4

3-D In-silico simulation of Tumor Spheroid induced Angiogenesis: (a) Early time; (b) Later time. The thin curves show vessel sprouts, the thick red curves describe blood-carrying vessels. The inner surface bounds the perine-crotic region. Figure courtesy of Dr. Fang Jin using methods described in [36,39].