Probing endogenous collagen by laser‐induced autofluorescence in burn wound biopsies: A pilot study

Abstract

The focus of the current study was to interrogate the predictive potential of laser-induced autofluorescence (LIAF) by objectively assessing collagen synthesis in burn wound granulation tissues ex vivo. Prior grafting, granulation tissues (20 samples) following burn injury were collected from 17 subjects of age range 18 to 60 years with patient/donor consent and the corresponding autofluorescence spectra were recorded at 325 nm He-Cd laser (≈2 mW) excitations. The resulting endogenous collagen intensity from the above tissue samples was computed by normalizing the nicotinamide adenine dinucleotide levels. In addition, the hydroxyproline content was also estimated biochemically from the same granulation tissues. A comparative assessment of both LIAF and biochemical estimations for endogenous collagen by hydroxyproline resulted in strong positive correlation among them. The above relevant observations suggest that LIAF is equally informative as that of biochemical estimations, in evaluating endogenous collagen content in wound granulation tissues. Thus, it can be concluded that LIAF has the predictive potential, as a noninvasive objective tool to measure the endogenous collagen levels in wound biopsy tissues and provide complementary data conducive for making clinical decisions.

Real‐time fiber‐based fluorescence lifetime imaging with synchronous external illumination: A new path for clinical translation

“…The application of autofluorescence measurements in clinical research was boosted by advances in light delivery and collection via fiber‐optic systems, which facilitated the development of optical techniques for non‐ and minimally invasive measurements of tissues, including in endoscopic and catheter procedures . The clinical potential and feasibility of autofluorescence measurements for in vivo clinical diagnosis have been demonstrated in a number of studies, either employing steady‐state , and/or time‐resolved autofluorescence measurements . Steady‐state autofluorescence intensity or emission spectroscopy have been widely employed in clinical diagnostic research and are by far more intensively exploited compared to time‐resolved measurements, mainly due to the simplicity and typically lower cost of the instrumentation involved.…”

Use of confocal microscopy imaging for in vitro assessment of adipose‐derived mesenchymal stromal cells seeding on acellular dermal matrices: 3D reconstruction based on collagen autofluorescence

“… 45 An Indian study focused on laser‐induced autofluorescence as a noninvasive objective tool to measure the endogenous collagen levels in burn wound granulation tissues ex vivo. 46 A group from California investigated the use of a fiber‐based, multispectral fluorescence lifetime imaging system to nondestructively monitor changes in mechanical properties of collagen hydrogels caused by controlled application of cross‐linking agents. 47 The authors observed strong and specific correlations between fluorescence lifetime and the storage or Young's moduli of the gels.…”

“…In 2011, Lutz et al analyzed collagen synthesis and structure using the signals second harmonic generation (SHG) and fluorescence lifetime of collagen autofluorescence by multiphoton laser scanning microscope 45 . An Indian study focused on laser‐induced autofluorescence as a noninvasive objective tool to measure the endogenous collagen levels in burn wound granulation tissues ex vivo 46 . A group from California investigated the use of a fiber‐based, multispectral fluorescence lifetime imaging system to nondestructively monitor changes in mechanical properties of collagen hydrogels caused by controlled application of cross‐linking agents 47 .…”

“…MFI is expressed in terms of positive pixels/field, obtained from measurements in three different areas (13 000 μm 2 ) of each of three randomly selected sections of every tissue sample. MFI of ADSC-seeded dermal scaffolds is significantly higher than control conditions (**p < 0.001) autofluorescence as a noninvasive objective tool to measure the endogenous collagen levels in burn wound granulation tissues ex vivo 46. A group from California investigated the use of a fiber-based, multispectral fluorescence lifetime imaging system to nondestructively monitor changes in mechanical properties of collagen hydrogels caused by controlled application of cross-linking agents 47.…”