Bedside hyperspectral imaging indicates a microcirculatory sepsis pattern - an observational study.

INTRODUCTION: Microcirculatory alterations are key mechanisms in sepsis pathophysiology leading to tissue hypoxia, edema formation, and organ dysfunction. Hyperspectral imaging (HSI) is an emerging imaging technology that uses tissue-light interactions to evaluate biochemical tissue characteristics including tissue oxygenation, hemoglobin content and water content. Currently, clinical data for HSI technologies in critical ill patients are still limited. METHODS AND ANALYSIS: TIVITA® Tissue System was used to measure Tissue oxygenation (StO2), Tissue Hemoglobin Index (THI), Near Infrared Perfusion Index (NPI) and Tissue Water Index (TWI) in 25 healthy volunteers and 25 septic patients. HSI measurement sites were the palm, the fingertip, and a suprapatellar knee area. Septic patients were evaluated on admission to the ICU (E), 6 h afterwards (E+6) and three times a day (t3-t9) within a total observation period of 72 h. Primary outcome was the correlation of HSI results with daily SOFA-scores. RESULTS: Serial HSI at the three measurement sites in healthy volunteers showed a low mean variance expressing high retest reliability. HSI at E demonstrated significantly lower StO2 and NPI as well as higher TWI at the palm and fingertip in septic patients compared to healthy volunteers. StO2 and TWI showed corresponding results at the suprapatellar knee area. In septic patients, palm and fingertip THI identified survivors (E-t4) and revealed predictivity for 28-day mortality (E). Fingertip StO2 and THI correlated to SOFA-score on day 2. TWI was consistently increased in relation to the TWI range of healthy controls during the observation time. Palm TWI correlated positively with SOFA scores on day 3. DISCUSSION: HSI results in septic patients point to a distinctive microcirculatory pattern indicative of reduced skin oxygenation and perfusion quality combined with increased blood pooling and tissue water content. THI might possess risk-stratification properties and TWI could allow tissue edema evaluation in critically ill patients. CONCLUSION: HSI technologies could open new perspectives in microcirculatory monitoring by visualizing oxygenation and perfusion quality combined with tissue water content in critically ill patients - a prerequisite for future tissue perfusion guided therapy concepts in intensive care medicine.

Evaluation of BMP2/miRNA co-expression systems for potent therapeutic efficacy in bone-tissue regeneration.

Reconstruction of bone defects and compensation of deficient repair mechanisms represent important goals within the field of regenerative medicine and require novel safe strategies for translation into the clinic. A non-viral osteogenic gene therapeutic vector system ('hybrid vectors') was generated, combining an improved bone morphogenetic protein 2 (BMP2) gene cassette and single pro-osteogenic microRNAs (miR-148b-3p, miR-20-5p, miR-590b-5p), driven by the U6 promoter. The vectors were tested in vitro for their osteogenic differentiation potential in C2C12 and C3H/10T1/2 cell lines, using BMP2 alone as control. After confirming BMP2 expression and miRNA transcription, increased osteogenic differentiation was observed by all hybrid vectors, but most consistently by BMP2/miR-590-5p, using alkaline phosphatase enzyme activity assays and osteogenic marker mRNA quantitation, including runt-related transcription factor 2 (Runx2), collagen type 1 (Col1a1) and osteocalcin. To visualise target mRNAs of the respective miRNAs, next generation sequencing was performed, confirming down-regulation of mRNA targets of the hybrid vectors. Since the hybrid vector consisting of BMP2 and miR-590-5p showed the largest increase in osteogenic differentiation in vitro, this was tested in a mouse ectopic-bone model. Mineralisation was more than with BMP2 alone. The present study showed hybrid vectors as a novel non-viral gene therapeutic plasmid system for combining therapeutic effects of recombinant protein expression and miRNA transcription that did not add to the burden of the translation machinery, while improving the therapeutic efficacies. In vivo proof-of-principle in the context of bone regeneration suggested that such hybrid vectors will be applicable in a wide array of gene therapeutic strategies.