Distinct microhemodynamic efficacy of arteriogenesis and angiogenesis in critically ischemic skin flaps

The effect of subperichondrial dissection on nasal vascularity in septorhinoplasty operations

PURPOSE

Nasal vascularization runs above the superficial musculoaponeurotic system (SMAS). Perichondrium covers the lower and upper lateral cartilages. In this study, nasal vascularization was compared between subperichondrial and supraperichondrial dissection in closed septorhinoplasty.

METHODS

95 patients and 41 volunteers were included in this study. Supraperichondrial dissection was performed in 48 patients and subperichondrial dissection was performed in 47 patients. To measure blood stream, laser doppler flowmetry (LDF) was used and measurements were done preoperatively, on the postoperative first week; 3rd month and first year.

RESULTS

The nasal tip and dorsum measurements were similar between the preoperative and postoperative first year in both groups (p = 1.000). However, in the supraperichondrial dissection group, nasal tip measurements showed a significant increase between the preoperative and third postoperative months (p = 0.011). This increase was accompanied by an increase in the minimal blood stream (p = 0.014).

CONCLUSION

Both subperichondrial and supraperichondrial dissection techniques are physiological and result in fewer complications with minimal permanent vascular damage. We believe incision plays a critical role but keeping the perichondrium intact is important for short-term angiogenesis, where long-term results showed no difference in vascularization.

Epinephrine penetrates through gingival sulcus unlike keratinized gingiva and evokes remote vasoconstriction in human

Background

It has been demonstrated in non-oral tissues that the locally evoked vasoconstriction could elicit remote vasoconstriction. This study aimed to investigate the spreading vasoconstrictor effects of epinephrine in the gingiva.

Methods

Gingival blood flow (GBF) was measured by laser speckle contrast imager in 21 healthy volunteers. In group A, two wells were fabricated from orthodontic elastic ligature and placed 2 mm apically to the free gingival margin at the mid buccal line of 12 (test side) and 21 (control side) teeth. The GBF was measured in the wells and tightly apical, coronal, distal and mesial to the wells. In group B, the wells were made on the buccal surface of the same teeth, including the gingival sulcus. Four regions were selected for measurement from the gingival margin reaching the mucogingival line (coronal, midway1, midway2 and apical). After the baseline recording, 3 µg epinephrine was applied into the test, and physiological saline into the control well. The GBF was recorded for 14 min. The gingival thickness was measured with a PIROP Ultrasonic Biometer.

Results

In group A, the GBF did not increase or decrease after the application of epinephrine. In group B, the GBF significantly decreased in all regions of the test side and remained low for the observation period. The vasoconstriction appeared with delays in more apical regions (at min 1 in the coronal and the midway1, at min 2 in the midway2, at min 4 in the apical region). Similarly, the amount of the decrease at 14 min was the largest close to sulcus (− 53 ± 2.9%), followed by the midway1 (− 51 ± 2.8%) and midway2 (− 42 ± 4.2%) and was the lowest in the apical region (− 32 ± 5.8%). No correlation was found between GBF and gingival thickness.

Conclusion

Epinephrine could evoke intense vasoconstriction propagating to the mucogingival junction, indicating the presence of spreading vasoconstriction in the human gingiva. The attached gingiva is impermeable to epinephrine, unlike the gingival sulcus.

This trial was registered in ClinicalTrials.gov titled as Evidence of Spreading Vasoconstriction in Human Gingiva with the reference number of NCT04131283 on 16 October 2019. https://clinicaltrials.gov/show/NCT04131283

In vivo imaging of hemodynamic redistribution and arteriogenesis across microvascular network

OBJECTIVE

Arteriogenesis is an important mechanism that contributes to restoration of oxygen supply in chronically ischemic tissues, but remains incompletely understood due to technical limitations. This study presents a novel approach for comprehensive assessment of the remodeling pattern in a complex microvascular network containing multiple collateral microvessels.

METHODS

We have developed a hardware-software integrated platform for quantitative, longitudinal, and label-free imaging of network-wide hemodynamic changes and arteriogenesis at the single-vessel level. By ligating feeding arteries in the mouse ear, we induced network-wide hemodynamic redistribution and localized arteriogenesis. The utility of this technology was demonstrated by studying the influence of obesity on microvascular arteriogenesis.

RESULTS

Simultaneously monitoring the remodeling of competing collateral arterioles revealed a new, inverse relationship between initial vascular resistance and extent of arteriogenesis. Obese mice exhibited similar remodeling responses to lean mice through the first week, including diameter increase and flow upregulation in collateral arterioles. However, these gains were subsequently lost in obese mice.

CONCLUSIONS

Capable of label-free, comprehensive, and dynamic quantification of structural and functional changes in the microvascular network in vivo, this platform opens up new opportunities to study the mechanisms of microvascular arteriogenesis, its implications in diseases, and approaches to pharmacologically rectify microvascular dysfunction.

Evidence of spreading vasodilation in the human gingiva evoked by nitric oxide

BACKGROUND AND OBJECTIVE

Spreading vasodilation is an important means of increasing local blood flow effectively during increased metabolic demands or in case of vascular injury. Our aim was to develop a technique proving the presence of spreading vasodilation in the human keratinized gingiva.

METHODS

Local vasodilation was evoked by the application of nitric oxide (NO) donor nitroglycerin into a well, fixed 2 mm above the marginal gingiva, in 20 subjects with healthy periodontal tissue. Either 1 or 8 mg/mL nitroglycerin solutions were dropped into the test well at the upper right second incisor, and saline was applied into the control well at the upper left first incisor. The gingival blood flow (GBF) was recorded for 15 minutes by a laser speckle contrast imager below the well and in the surrounding area in the mesial, distal, apical and coronal directions. Gingival thickness was measured by an ultrasonic biometer.

RESULTS

Peak GBF increase was similar after 1 mg/mL and after 8 mg/mL nitroglycerin application in the well (51% ± 12% vs 42% ± 8%) and in the apical region (33 ± 9% vs 55% ± 13%). While the lower dose of nitroglycerin increased GBF only in the apical region around the well, the higher dose induced significant elevations in all surrounding regions, with apical prominence. Hyperaemia lasted 10-14 minutes in the low-dose group whereas it extended beyond the observation period in the high-dose group. Neither the baseline nor the NO-induced peak GBF were correlated with gingival thickness.

CONCLUSION

The role of the direct effect of NO in the regulation of perfusion was demonstrated in the human gingiva as well as the propagation of local vasodilation to distant, especially apical areas, probably by the mechanism of flow-mediated dilation. This mechanism may have a clinical importance for flap survival or wound healing.

Evaluation of Laser Speckle Contrast Imaging for the Assessment of Oral Mucosal Blood Flow following Periodontal Plastic Surgery: An Exploratory Study

The laser speckle contrast imaging (LSCI) is proved to be a reliable tool in flap monitoring in general surgery; however, it has not been evaluated in oral surgery yet. We applied the LSCI to compare the effect of a xenogeneic collagen matrix (Geistlich Mucograft®) to connective tissue grafts (CTG) on the microcirculation of the modified coronally advanced tunnel technique (MCAT) for gingival recession coverage. Gingival microcirculation and wound fluid were measured before and after surgery for six months at twenty-seven treated teeth. In males, the flap microcirculation was restored within 3 days for both grafts followed by a hyperemic response. During the first 8 days the blood flow was higher at xenogeneic graft comparing to the CTG. In females, the ischemic period lasted for 7–12 days depending on the graft and no hyperemic response was observed. Females had more intense and prolonged wound fluid production. The LSCI method is suitable to capture the microcirculatory effect of the surgical intervention in human oral mucosa. The application of xenogeneic collagen matrices as a CTG substitute does not seem to restrain the recovery of graft bed circulation. Gender may have an effect on postoperative circulation and inflammation.

Severe mutilating injuries with complex macroamputations of the upper extremity - is it worth the effort?

Introduction

An amputation of the upper extremity and the following replantation is still one of the most challenging operations in the field of reconstructive surgery, especially in extremely severe cases of combined mutilating macroamputations including avulsion and multilevel injuries. Specialists agree that macroamputations with sharp wound edges are an absolute indication for replantation. However, there is no agreement in disastrous cases including avulsion and multilevel injuries. The outcome of the operation is depending on several factors, including the type of accident, age and pre-existing disease of the patient, as well as time of ischemia and appropriate physical therapy.

Methods

Between January 1^st 2003 and December 31^st 2011 six patients underwent a macroreplantation with disastrous combined and complex injuries of the upper extremity in our department. We performed a follow up and evaluated the functional outcome of the upper extremity function using the DASH questionnaire (average follow up of 3.1 years).

Results

The mean time of ischemia was 04:50 h (02:46 h–06:17 h). The mean time for the operation was 05:30 h (01:55 h–08:20 h). The mean operations needed per patient were 7 (2–16). The average hospital stay was 29d (16–59d). According to the DASH-Score from five out of six patients the functional outcome of the replanted extremity has a mean score of 71 points. The versatility of the replanted extremity in the field of work had 95, and sport, music was assessed with a mean score of 96 points.

Conclusions

Severe and disastrous combined and complex macroamputations of the upper extremity may also have an absolute indication for replantation even though the functional outcome is poor. Not only the feeling of physical integrity can be restored, but the replantation of an amputated upper extremity enables complete or partial recovery of function and sensibility of the arm which is important for the individual. Although our results show a very high DASH-Score, those achievements justify time and person consuming operations. In most cases a replanted extremity is still superior to a secondary allotransplantation. Usually the use of prosthesis is not favored by the treated patients.

Bone marrow-derived mesenchymal stromal cells improve vascular regeneration and reduce leukocyte-endothelium activation in critical ischemic murine skin in a dose-dependent manner

BACKGROUND AIMS

Stem cells participate in vascular regeneration following critical ischemia. However, their angiogenic and remodeling properties, as well as their role in ischemia-related endothelial leukocyte activation, need to be further elucidated. Herein, we investigated the effect of bone marrow-derived mesenchymal stromal cells (BM-MSCs) in a critically ischemic murine skin flap model.

METHODS

Groups received either 1 × 10(5), 5 × 10(5), or 1 × 10(6) BM-MSCs or cell-free conditioned medium (CM). Controls received sodium chloride. Intravital fluorescence microscopy was performed for morphological and quantitative assessment of micro-hemodynamic parameters over 12 days.

RESULTS

Tortuosity and diameter of conduit-arterioles were pronounced in the MSC groups (P < 0.01), whereas vasodilation was shifted to the end arteriolar level in the CM group (P < 0.01). These effects were accompanied by angiopoietin-2 expression. Functional capillary density and red blood cell velocity were enhanced in all treatment groups (P < 0.01). Although a significant reduction of rolling and sticking leukocytes was observed in the MSC groups with a reduction of diameter in postcapillary venules (P < 0.01), animals receiving CM exhibited a leukocyte-endothelium interaction similar to controls. This correlated with leukocyte common antigen expression in tissue sections (P < 0.01) and p38 mitogen-activated protein kinase expression from tissue samples. Cytokine analysis from BM-MSC culture medium revealed a 50% reduction of pro-inflammatory cytokines (interleukin [IL]-1β, IL-6, IL-12, tumor necrosis factor-α, interferon-γ) and chemokines (keratinocyte chemoattractant, granulocyte colony-stimulating factor) under hypoxic conditions.

DISCUSSION

We demonstrated positive effects of BM-MSCs on vascular regeneration and modulation of endothelial leukocyte adhesion in critical ischemic skin. The improvements after MSC application were dose-dependent and superior to the use of CM alone.