Using bimodal MRI/fluorescence imaging to identify host angiogenic response to implants

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Regenerative Medicine

Background:

• Angiogenesis therapies utilize proangiogenic factors with biodegradable delivery vehicles.
• Host response to biomaterials is critical for therapeutic efficacy.

Purpose of the Study:

• To investigate how implantation mode and implant material surface area-to-volume ratio affect host response.
• To evaluate the degradation and bioactive constituent release from different VEGF-bearing hydrogel configurations in vivo.

Main Methods:

• Utilized bimodal noninvasive monitoring (Fluorescence/MRI) of VEGF-bearing PEG-fibrinogen hydrogel implants in a rat model.
• Compared three implant configurations: in situ polymerized hydrogel, injectable microbeads, and preformed cylindrical plugs.
• Quantified hydrogel biodegradation, release profiles, and subsequent host angiogenic response.

Main Results:

• In situ polymerized hydrogels degraded within 2 weeks, microbeads moderately, and plugs slowly.
• Distinct biphasic release profiles of degradation products and VEGF were observed for each configuration.
• Microbead implants led to highly vascularized tissue with up to 16-fold more capillaries compared to controls.

Conclusions:

• Implant configuration critically influences hydrogel degradation kinetics and resorption.
• Material design and implantation strategy significantly modulate the host angiogenic response.
• Optimizing implant configuration is key for effective delivery of proangiogenic factors and tissue regeneration.