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Fractal characteristics of tumor vascular architecture during tumor growth and regression
Y Gazit1, J W Baish, N Safabakhsh
1Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, USA.
Objective:
Tumor vascular networks are different from normal vascular networks, but the mechanisms underlying these differences are not known. Understanding these mechanisms may be the key to improving the efficacy of treatment of solid tumors.
Methods:
We studied the fractal characteristics of two-dimensional normal and tumor vascular networks grown in a murine dorsal chamber preparation and imaged with an intravital microscopy station.
Results:
During tumor growth and regression, the vasculature in the tumor has scaling characteristics that reflect the changing state of the tissue. Growing tumors show vascular networks that progressively deviate from their normal pattern, in which they seem to follow diffusion-limited aggregation to a pathological condition in which they display scaling similar to percolation clusters near the percolation threshold. The percolation-like scaling indicates that the key determinants of tumor vascular architecture are local substrate properties rather than gradients of a diffusing substance such as an angiogenic growth factor. During tumor regression the fractal characteristics of the vasculature return to an intermediate between those of growing tumors and those of healthy tissues. Previous studies have shown that percolation-like scaling generally inhibits transport.
Conclusions:
In the present context, the percolation-like nature of tumor vasculature implies that tumor vascular networks possess inherent architectural obstacles to the delivery of diffusible substances such as oxygen and drugs.
Insights
Tumor vascular networks exhibit unique fractal patterns, resembling percolation clusters, which hinder oxygen and drug delivery. Understanding these architectural differences is crucial for improving cancer treatments.
Area of Science:
- Vascular biology
- Cancer research
- Biophysics
Background:
- Tumor vascular networks differ significantly from normal vasculature.
- The underlying mechanisms driving these differences remain largely unknown.
- Understanding tumor vascular architecture is vital for enhancing solid tumor treatment efficacy.
Purpose of the Study:
- To investigate the fractal characteristics of normal and tumor vascular networks.
- To elucidate the mechanisms governing tumor vascular architecture.
- To correlate vascular network structure with tumor growth and regression.
Main Methods:
- Studied fractal characteristics of 2D normal and tumor vascular networks.
- Utilized a murine dorsal chamber preparation.
- Imaged vascular networks using intravital microscopy.
Main Results:
- Tumor vasculature exhibits scaling characteristics that change with tumor growth and regression.
- Growing tumors display vascular networks deviating from normal patterns, resembling percolation clusters.
- Percolation-like scaling suggests local substrate properties, not growth factors, dictate tumor vascular architecture.
- Tumor regression leads to vascular fractal characteristics intermediate between growing tumors and healthy tissues.
Conclusions:
- The percolation-like nature of tumor vasculature creates inherent architectural obstacles.
- These obstacles impede the delivery of diffusible substances like oxygen and drugs.
- This finding has significant implications for the efficacy of cancer therapies targeting drug and oxygen delivery.