Bridging the Gap in Relation to Nerve Injury

__Abstract__ The title of this thesis has been chosen after careful reflection. The different meanings reflect the research performed in this thesis: - Nerve regeneration after bridging a large nerve defect is an important subject of this thesis. - The second interpretation of this title should be sought in the translational aspect of this thesis. We tried to implement the use of Bone Marrow Stromal Cells (BMSCs) in nerve reconstruction in a conduit often used in clinical setting. A bench to bedside approach! - The third interpretation refers to the bridge between experimental and human research. In this thesis both types of studies have been conducted to answer research questions related to nerve injury and one aspect of clinical follow-up, i.e. cold intolerance

Gene expression and growth factor analysis in early nerve regeneration following segmental nerve defect reconstruction with a mesenchymal stromal cell-enhanced decellularized nerve all

Background: The purpose of this study was to evaluate the molecular mechanisms underlying nerve repair by a decellularized nerve allograft seeded with adiposederived mesenchymal stromal cells (MSCs) and compare it to the unseeded allograft and autograft nerve. Methods: Undifferentiated MSCs were seeded onto decellularized nerve allografts and used to reconstruct a 10 mm gap in a rat sciatic nerve model. Gene expression profiles of genes essential for nerve regeneration and immunohistochemical staining (IHC) for PGP9.5, NGF, RECA-1, and S100 were obtained 2 weeks postoperatively. Results: Semi-quantitative RT-PCR analysis showed that the angiogenic molecule VEGFA was significantly increased in seeded allografts, and transcription factor SOX2 was downregulated in seeded allografts. Seeded grafts showed a significant increase in immunohistochemical markers NGF and RECA-1, when compared with unseeded allografts. Conclusions: MSCs contributed to the secretion of trophic factors. A beneficial effect of the MSCs on angiogenesis was found when compared with the unseeded nerve allograft, but implanted MSCs did not show evidence of differentiation into Schwann cell-like cells

A New Approach to Assess the Gastrocnemius Muscle Volume in Rodents Using Ultrasound; Comparison with the Gastrocnemius Muscle Index

Introduction: The purpose of this study was to determine the reliability and validity of a new non-invasive ultrasound technique to measure gastrocnemius muscle atrophy after nerve denervation in an animal model. Methods: In sixteen rodents an eight mm sciatic nerve gap was created. In the following 8 weeks, each week, two rodents were euthanized and the gastrocnemius muscle was examined using two different ultrasound systems and two investigators. The standardized ultrasound measurement protocol consisted of identifying pre-defined anatomical landmarks: 1) the fibula, 2) the fibular nerve, and 3) the junction between the most distal point of the semitendinosus muscle and gastrocnemius muscle. Consequently, we measured the muscle thickness as the length of the line between the fibula and the junction between the two muscles, perpendicular to the fibular nerve. After the ultrasound recording, the muscle mass was determined. Results: A steep decline of muscle weight of 24% was observed after one week. In the following weeks, the weight further decreased and then remained stable from 6 weeks onwards, resulting in a maximal muscle weight decrease of 82%. The correlation coefficient was >0.96 between muscle diameter and weight using both ultrasound systems. The inter-rater reliability was excellent for both devices on the operated side (ICC of 0.99 for both ultrasound systems) and good for the non-operated site (ICC's: 0.84 & 0.89). The difference between the muscle mass ratio and the muscle thickness ratio was not more than 5% with two outliers of approximately 13%. Discussion: We have developed an innovative, highly reliable technique for quantifying muscle atrophy after nerve injury. This technique allows serial measurements in the same animal over time. This is a significant advantage compared to the conventional technique for quantifying muscle atrophy, which requires sacrificing the animal

Application of hydrosurgery for burn wound debridement: An 8-year cohort analysis

Introduction: During the last decade, the Versajet™ hydrosurgery system has become popular as a tool for tangential excision in burn surgery. Although hydrosurgery is thought to be a more precise and controlled manner for burn debridement prior to skin grafting, burn specialists decide individually whether hydrosurgery should be applied in a specific patient or not. The aim of this study was to gain insight in which patients hydrosurgery is used in specialized burn care in the Netherlands. Methods: A retrospective study was conducted in all patients admitted to a Dutch burn centre between 2009 and 2016. All patients with burns that underwent surgical debridement were included. Data were collected using the national Dutch Burn Repository R3. Results: Data of 2113 eligible patients were assessed. These patients were treated with hydrosurgical debridement (23.9%), conventional debridement (47.7%) or a combination of these techniques (28.3%). Independent predictors for the use of hydrosurgery were a younger age, scalds, a larger percentage of total body surface area (TBSA) burned, head and neck burns and arm burns. Differences in surgical management and clinical outcome were found between the three groups. Conclusion: The use of hydrosurgery for burn wound debridement prior to skin grafting is substantial. Independent predictors for the use of hydrosurgery were mainly burn related and consisted of a younger age, scalds, a larger TBSA burned, and burns on irregularly contoured body areas. Randomized studies addressing scar quality are needed to open new perspectives on the potential benefits of hydrosurgical burn wound debridement

Long-term scar quality after hydrosurgical versus conventional debridement of deep dermal burns (HyCon trial): Study protocol for a randomized controlled trial

Background: Deep dermal burns require tangential excision of non-viable tissue and skin grafting to improve wound healing and burn-scar quality. Tangential excision is conventionally performed with a knife, but during the last decade hydrosurgery has become popular as a new tool for tangential excision. Hydrosurgery is generally thought to be a more precise and controlled manner of burn debridement leading to preservation of viable tissue and, therefore, better scar quality. Although scar quality is considered to be one of the most important outcomes in burn surgery today, no randomized controlled study has compared the effect of these two common treatment modalities with scar quality as a primary outcome. The aim of this study is, therefore, to compare long-term scar quality after hydrosurgical versus conventional tangential excision in deep dermal burns. Methods/design: A multicenter, randomized, intra-patient, controlled trial will be conducted in the Dutch burn centers of Rotterdam, Beverwijk, and Groningen. All patients with deep dermal burns that require excision and grafting are eligible. Exclusion criteria are: a burn wound 30%, full-thickness burns, chemical or electrical burns, infected wounds (clinical symptoms in combination with positive wound swabs), insufficient knowledge of the Dutch or English language, patients that are unlikely to comply with requirements of the study protocol and follow-up, and patients who are (temporarily) incompetent because of sedation and/or intubation. A total of 137 patients will be included. Comparable wound areas A and B will be appointed, randomized and either excised conventionally with a knife or with the hydrosurgery system. The primary outcome is scar quality measured by the observer score of the Patient and Observer Scar Assessment Scale (POSAS); a subjective scar-assessment instrument, consisting of two separate six-item scales (observer and patient) that are both scored on a 10-point rating scale. Discussion: This study will contribute to the optimal surgi