Type 1 diabetes (T1D) is an autoimmune disease that leads to the destruction of pancreatic islets, resulting in the deficiency of insulin secretion. The current treatment is a daily insulin injection regimen, which negatively affects the quality of life for T1D patients and is difficult to manage over an entire lifespan. Therefore, an alternative treatment – islet transplantation within implantable devices – has been regarded as a promising therapy to achieve insulin-independence. Nevertheless, the interplay of implant surface and recipient tissue can result in a foreign body response (FBR) which is one of the main reasons for implant failure. The encapsulation isolates the implant from surrounding tissues, impeding it from nutrients, oxygen and drug molecule diffusion. In this study, a non-invasive method, Raman microspectroscopy (RM), was utilized to investigate the characterization of the extracellular matrix (ECM) within the fibrotic capsule, which can be utilized for future application in medical device assessment.
In this study, implantable devices were analyzed in regard to their potential to induce the FBR. A marker-independent approach via RM was applied to investigate the fibrotic capsule. True Component Analysis (TCA) was utilized to generate intensity distribution images for ECM components. ECM proteins were identified and validated by immunofluorescence (IF) staining. Principal component analysis (PCA) was conducted to assess further molecular information.
Fibrotic capsule structures could be identified by RM as well as IF and histological staining. Raman imaging and TCA allowed the identification, localization and quantification of collagen I, collagen III as well as α-SMA. PCA of extracted collagen I spectra indicated differences between collagen structures of fibrotic capsule and connective tissue, represented by shifts in Raman bands assigned to amide I and III, phenylalanine and hydroxyproline. This study demonstrated that RM has the potential to examine the severity of the FBR.