Paola Koenen

Acute and chronic wound fluids inversely influence adipose‐derived stem cell function: molecular insights into impaired wound healing

Wound healing is a complex biological process that requires a well‐orchestrated interaction of mediators as well as resident and infiltrating cells. In this context, mesenchymal stem cells play a crucial role as they are attracted to the wound site and influence tissue regeneration by various mechanisms. In chronic wounds, these processes are disturbed. In a comparative approach, adipose‐derived stem cells (ASC) were treated with acute and chronic wound fluids (AWF and CWF, respectively). Proliferation and migration were investigated using 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) test and transwell migration assay. Gene expression changes were analysed using quantitative real time–polymerase chain reaction. AWF had a significantly stronger chemotactic impact on ASC than CWF (77·5% versus 59·8% migrated cells). While proliferation was stimulated by AWF up to 136·3%, CWF had a negative effect on proliferation over time (80·3%). Expression of b‐FGF, vascular endothelial growth factor (VEGF) and matrix metalloproteinase‐9 was strongly induced by CWF compared with a mild induction by AWF. These results give an insight into impaired ASC function in chronic wounds. The detected effect of CWF on proliferation and migration of ASC might be one reason for an insufficient healing process in chronic wounds.

The role of SDF‐1 in homing of human adipose‐derived stem cells

One of the putative pathophysiological mechanisms of chronic wounds is a disturbed homing of stem cells. In this project, the stromal cell‐derived factor 1 (SDF‐1)/C‐X‐C chemokine receptor (CXCR) 4 and SDF‐1/CXCR7 pathway were focused in human adipose‐derived stem cells (ASCs). ASCs were incubated with acute (AWF) or chronic wound fluid (CWF) to analyze their effects by quantitative real‐time polymerase chain reaction (SDF‐1, CXCR4, CXCR7, TIMP3), enzyme‐linked immunosorbent assay (SDF‐1 in WFs and supernatant), and transwell migration assay with/without antagonization. Whereas SDF‐1 amounted 73.5 pg/mL in AWF, it could not be detected in CWF. Incubation with AWF led to a significant enhancement (129.7 pg/mL vs. 95.5 pg/mL), whereas CWF resulted in a significant reduction (30 pg/mL vs. 95.5 pg/mL) of SDF‐1 in ASC supernatant. The SDF‐1 receptor CXCR7 was detected on ASCs. AWF but not CWF significantly induced ASC migration, which was inhibited by CXCR4 and CXCR7 antagonists. Expressions of SDF‐1, CXCR4, and CXCR7 were significantly stimulated by AWF while TIMP3 expression was reduced. In conclusion, an uncontrolled inflammation in the chronic wound environment, indicated by a reduced SDF‐1 expression, resulted in a decreased ASC migration. A disturbed SDF‐1/CXCR4 as well as SDF‐1/CXCR7 pathway seems to play an important role in the impaired healing of chronic wounds.

Acute and chronic wound fluids influence keratinocyte function differently

Wound healing requires a proper functioning of keratinocytes that migrate, proliferate and lead to a competent wound closure. Impaired wound healing might be due to a disturbed keratinocyte function caused by the wound environment. Basically, chronic wound fluid (CWF) differs from acute wound fluid (AWF). The aim of this study was to analyse the effects of AWF and CWF on keratinocyte function. We therefore investigated keratinocyte migration and proliferation under the influence of AWF and CWF using MTT [3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide] test and scratch assay. We further measured the gene expression by qRT‐PCR regarding growth factors and matrixmetalloproteinases (MMPs) involved in regeneration processes. AWF had a positive impact on keratinocyte proliferation over time, whereas CWF had an anti‐proliferative effect. Keratinocyte migration was significantly impaired by CWF in contrast to an undisturbed wound closure under the influence of AWF. MMP‐9 expression was strongly upregulated by CWF compared with AWF. Keratinocyte function was significantly impaired by CWF. An excessive induction of MMP‐9 by CWF might lead to a permanent degradation of extracellular matrix and thereby prevent wounds from healing.

Adipose‐derived stem cells and keratinocytes in a chronic wound cell culture model: the role of hydroxyectoine

Chronic wounds represent a major socio‐economic problem in developed countries today. Wound healing is a complex biological process. It requires a well‐orchestrated interaction of mediators, resident cells and infiltrating cells. In this context, mesenchymal stem cells and keratinocytes play a crucial role in tissue regeneration. In chronic wounds these processes are disturbed and cell viability is reduced. Hydroxyectoine (HyEc) is a membrane protecting osmolyte with protein and macromolecule stabilising properties. Adipose‐derived stem cells (ASC) and keratinocytes were cultured with chronic wound fluid (CWF) and treated with HyEc. Proliferation was investigated using MTT test and migration was examined with transwell‐migration assay and scratch assay. Gene expression changes of basic fibroblast growth factor (b‐FGF), vascular endothelial growth factor (VEGF), matrix metalloproteinases‐2 (MMP‐2) and MMP‐9 were analysed by quantitative real‐time polymerase chain reaction (qRT‐PCR). CWF significantly inhibited proliferation and migration of keratinocytes. Addition of HyEc did not affect these results. Proliferation capacity of ASC was not influenced by CWF whereas migration was significantly enhanced. HyEc significantly reduced ASC migration. Expression of b‐FGF, VEGF, MMP‐2 and MMP‐9 in ASC, and b‐FGF, VEGF and MMP‐9 in keratinocytes was strongly induced by chronic wound fluid. HyEc enhanced CWF induced gene expression of VEGF in ASC and MMP‐9 in keratinocytes. CWF negatively impaired keratinocyte function, which was not influenced by HyEc. ASC migration was stimulated by CWF, whereas HyEc significantly inhibited migration of ASC. CWF induced gene expression of VEGF in ASC and MMP‐9 in keratinocytes was enhanced by HyEc, which might partly be explained by an RNA stabilising effect of HyEc.

Reliable Alignment in Total Knee Arthroplasty by the Use of an iPod-Based Navigation System

Axial alignment is one of the main objectives in total knee arthroplasty (TKA). Computer-assisted surgery (CAS) is more accurate regarding limb alignment reconstruction compared to the conventional technique. The aim of this study was to analyse the precision of the innovative navigation system DASH® by Brainlab and to evaluate the reliability of intraoperatively acquired data. A retrospective analysis of 40 patients was performed, who underwent CAS TKA using the iPod-based navigation system DASH. Pre- and postoperative axial alignment were measured on standardized radiographs by two independent observers. These data were compared with the navigation data. Furthermore, interobserver reliability was measured. The duration of surgery was monitored. The mean difference between the preoperative mechanical axis by X-ray and the first intraoperatively measured limb axis by the navigation system was 2.4°. The postoperative X-rays showed a mean difference of 1.3° compared to the final navigation measurement. According to radiographic measurements, 88% of arthroplasties had a postoperative limb axis within ±3°. The mean additional time needed for navigation was 5 minutes. We could prove very good precision for the DASH system, which is comparable to established navigation devices with only negligible expenditure of time compared to conventional TKA.

Comparison of transportation related injury mechanisms and outcome of young road users and adult road users, a retrospective analysis on 24,373 patients derived from the TraumaRegister DGU ®

BackgroundMost young people killed in road crashes are known as vulnerable road users. A combination of physical and developmental immaturity as well as inexperience increases the risk of road traffic accidents with a high injury severity rate. Understanding injury mechanism and pattern in a group of young road users may reduce morbidity and mortality. This study analyzes injury patterns and outcomes of young road users compared to adult road users. The comparison takes into account different transportation related injury mechanisms.MethodsA retrospective analysis using data collected between 2002 and 2012 from the TraumaRegister DGU® was performed. Only patients with a transportation related injury mechanism (motor vehicle collision (MVC), motorbike, cyclist, and pedestrian) and an ISS ≥ 9 were included in our analysis. Four different groups of young road users were compared to adult trauma data depending on the transportation related injury mechanism.ResultsTwenty four thousand three hundred seventy three, datasets were retrieved to compare all subgroups. The mean ISS was 23.3 ± 13.1. The overall mortality rate was 8.61%. In the MVC, the motorbike and the cyclist group, we found young road users having more complex injury patterns with a higher AIS pelvis, AIS head, AIS abdomen and AIS of the extremities and also a lower GCS. Whereas in these three sub-groups the adult trauma group only had a higher AIS thorax. Only in the group of the adult pedestrians we found a higher AIS pelvis, AIS abdomen, AIS thorax, a higher AIS of the extremities and a lower GCS.DiscussionThis study reports on the most common injuries and injury patterns in young trauma patients in comparison to an adult trauma sample. Our analysis show that in contrast to more experienced road users our young collective refers to be a vulnerable trauma group with an increased risk of a high injury severity and high mortality rate. We indicate a striking difference in terms of the region of injury and the mechanism of injury when comparing the young versus the adult trauma collectives.ConclusionsYoung drivers of cars, motorbikes and bikes were shown to be on high risk to sustain a specific severe injury pattern and a high mortality rate compared to adult road users. Our data emphasize a characteristic injury pattern of young trauma patients and may be used to improve trauma care and to guide prevention strategies to decrease injury severity and mortality due to road traffic injuries.

Early single-shot intravenous steroids do not affect pulmonary complications and mortality in burned or scalded patients

BACKGROUND AND OBJECTIVES Inhalation injury, especially in combination with cutaneous burns, is the major cause of morbidity and mortality in patients admitted to burn care centers. Either with or without the presence of a cutaneous burn, inhalation injury contributes to high risk for developing severe pulmonary complications. Steroids may reduce a prolonged and destructive inflammatory response to toxic or allergic substances. The objective of this study was to evaluate the effect of early single-shot intravenous steroids on pulmonary complications and mortality in burned or scalded patients with or without inhalation injury. METHODS Retrospective analysis of a prospective single center database of patients registered between 1989 and 2011 who were admitted to the intensive care unit of our burn care center after burn or scald injury. Uni-variate statistical analysis was performed comparing two groups (steroid treated vs. non steroid treated patients) with regard to clinical outcome. Main parameters were sepsis, mortality and pulmonary complications such as pneumonia, ALI and ARDS. Multi-variate analysis was used by logistic regression with mortality and pulmonary complications as the dependent variables to identify independent risk factors after burn or scald injuries. RESULTS A total of 1637 patients with complete data were included in the present analysis. 199 (12.2%) received single-shot intravenous steroids during the prehospital phase of care. In 133 (66.8%) of these patients, inhalation injury was diagnosed via bronchoscopy. Steroid treated patients had sustained a significantly higher severity of burn than non-steroid treated patients (Abbreviated Burn Severity Index 7.1±3 vs. 6.0±2.9; p<0.001). In a multivariate analysis using a logistic regression model early intravenous steroid treatment had no significant effect on pulmonary complications and mortality. CONCLUSIONS In our single center cohort of burned and scalded patients single-shot intravenous steroids during the pre-hospital phase of care was not associated with pulmonary complications or mortality.

The Impact of Pinless Navigation in Conventionally Aligned Total Knee Arthroplasty

Background Restoration of the mechanical axis is a main objective in total knee replacement (TKR). Aim of this study was to analyse the verification tool of a pinless navigation system in conventional TKR (cTKR). Methods In a prospective study, 147 TKR were performed by conventional technique. Using the “pinless verification” mode of a smartphone based navigation system, the cutting block position and final resection plane for distal femur and proximal tibial resection were measured. If necessary, the block position or resection level were optimized, corrections were protocolled. Postoperatively, standardized radiographs were performed. Results In 65.3%, intraoperative measurements changed the surgical procedure (corrections: 20.4% femoral, 25.9% tibial, 19% both). The additional time for surgery compared to cTKR averaged 6 minutes (79 ± 15 versus 73 ± 17 minutes). Using navigation data, the final femoral and tibial axes were in 93% within a range of ±2°. A mean difference of 1.4° and 1.6° could be shown between the final measurement of the navigation system and the postoperative mLDFA and mMPTA. Conclusion Intraoperative pinless navigation has impact on the surgical procedure in the majority of cTKR. It represents a less time-consuming tool to improve implant position while maintaining the routine of conventional technique.

The influence of an injury prevention program on young road users: a German experience

PurposeTrauma remains a leading cause of mortality and morbidity in youth. The Prevent Alcohol and Risk Related Trauma in Youth (P.A.R.T.Y.) program is an injury prevention program. The aim of the study was to analyze the influence on risk-taking behaviors and risk awareness on young road users by a pre–post-questionnaire.MethodsA pre–post intervention study was performed using a standardized questionnaire. The questionnaire contained three sections with different items (in total 22) to identify differences regarding students’ risk behavior and risk awareness. Data were analyzed using the Wilcoxon signed-rank test with significance defined as p < 0.05.ResultsThe study sample contains 193 students (age 14–17, 44% male). We found significant differences for asking if a student “fastens his/her helmet’s chinstrap when driving a motorbike” (p = 0.001) and for the question “Do you wear a helmet when you go rollerblading” (p = 0.008). After attending the program, participants would decrease the use of a mobile phone while driving (p = 0.038) and the understanding of the risk “speeding” and “cycling without a helmet” significantly increased.ConclusionsThe P.A.R.T.Y. program focuses on items like “use of helmet and mobile phones” and “alcohol/drug abuse”. Evaluating the program helps to uncover vulnerabilities and to enhance important effects. Some of these items are addressed by the program, whereas some are not. It will be important to improve the program according to address topics that have not shown significant improvements, so that students learn more about the dangers and the right behavior in road traffic.

Transosseous Repair of Root Tears of the Lateral Meniscus: Operative Technique and Short-Term Clinical Follow-Up of 28 Patients

An avulsion of the posterior tibial insertion of the lateral meniscus occurs during rotational distortion of the knee and can be associated with a tear of the anterior cruciate ligament (ACL). We performed a follow-up of 28 patients who, following anatomical ACL reconstruction using the ipsilateral semitendinosus graft, underwent either transosseous repair of the posterior lateral meniscus root () or no intervention (). The meniscus root tears were classified as Forkel I lesions. All patients were examined 6 months after surgery and undertook scoring using International Knee Documentation Committee Score (IKDC). Comparing the repair group with the no repair group the subjective IKDC 6 months after surgery was 75,72% (±1,019) and 75,56 (±1,058). Regarding the objective IKDC 8 × A (57,1%) and 6 × B (42,9%) could be ascertained in the repair group whereas 6 × A (42,9%), 6 × B (42,9%), and 2 × C (14,3%) scoring could be ascertained in the no repair group. It remains unclear if surgery on type Forkel I PLMRT provides benefits compared to the nonsurgical procedures as in both groups stability might occur. The purpose of this article was to report the outcome of surgical repair of lateral meniscus root tears.