Timm P. Wolter

Platelet-rich plasma in burns

Platelet-rich plasma stimulates angiogenesis, promoting vascular in-growth and fibroblast proliferation. In addition, PRP functions as haemostatic by forming a fibrin clot. Also application of PRP enhances wound-healing in both soft and hard tissue. A survey of the literature to assess the current clinical experience and the possible effects of platelet-rich plasma (PRP) on wound-healing in burn cases yields only few reports. The application of PRP is not currently standardized and the effects in wound-healing are poorly understood. The use of PRP as an analog to fibrin sealant is also only seldomly reported. The value of PRP application in burns remains unclear. A definitive assessment as to the application of PRP in burn treatment will require further studies. Theoretically the effects of PRP in burn wounds could be beneficial, however the interaction in tissue repair and regeneration must be better understood.

Content of the growth factors bFGF, IGF-1, VEGF, and PDGF-BB in freshly harvested lipoaspirate after centrifugation and incubation.

Background: In autologous fat transfer, several questions regarding basic biochemical properties of the transplant remain unanswered. Basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF), vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF)-BB have been shown to improve transplantation results. However, no study regarding naturally occurring levels of growth factors in transplanted adipose tissue has yet been performed. In addition, there are no data as to whether intraoperative refinement eliminates or concentrates growth factors. Methods: The authors investigated the content of bFGF, IGF, VEGF, and PDGF-BB in freshly aspirated adipose tissue and the presence of those factors in the various fractions after centrifugation by means of enzyme-linked immunosorbent assay readings. They also analyzed growth factor content after storage periods of 3 and 5 days and investigated the vitality of freshly centrifuged adipose tissue by staining with Hoechst 33342 and propidium iodide. Results: The authors found significant quantities of bFGF, IGF-1, VEGF, and PDGF-BB (39.9, 113.8, 3.0, and 5.8 pg/mg, respectively) in the lipoaspirate harvested for transplantation. Separation by centrifugation and discarding of the infranatant and supernatant fluid means that most of the growth factors are left in the transplant. The growth factor content in the other fractions was significantly lower. Lipoaspirate can be cultured for several days, with the tissue remaining biologically active and producing significant growth factor levels. Conclusion: Knowledge of the naturally occurring range for these growth factor quantities will enable researchers and clinicians to make autologous fat transfer procedures more reliable and safe.

A 5-year assessment of safety and aesthetic results after facial soft-tissue augmentation with polyacrylamide hydrogel (Aquamid): a prospective multicenter study of 251 patients.

Background: The permanent filler polyacrylamide hydrogel (Aquamid) has been used for soft-tissue augmentation for more than 16 years. To evaluate the safety and efficacy of the material, the manufacturer initiated in 2001 a prospective clinical trial with a follow-up of 5 years. This represents one of the longest running studies on currently used fillers. Methods: Two hundred fifty-one patients were enrolled in a noncomparative, prospective study and followed at 15 sites in Europe. The follow-up rates were 228 (90.8 percent), 101 (40.2 percent), 81 (32.3 percent), and 116 (46.2 percent) for the 12-, 24-, 36/48-, and 60-month follow-up periods. Patients received an average of 4.3 ml of Aquamid during an average of 2.4 injection sessions. Preferred areas were the nasolabial folds (37 percent) and the lips (28 percent). Study parameters were cosmetic outcome, blood analysis, and recording of local or generalized symptoms, including adverse reactions. Results: Aesthetic outcome was rated as “very good” or “good” by 96.5 percent of patients and by 96.0 percent of investigators at final available follow-up. During the entire study period, a total of 53 adverse events and two serious adverse events were classified as treatment related. Thirteen adverse events were gel indurations and four cases of infection were seen. All had been resolved within the study period. Conclusions: The study showed a very good aesthetic outcome and few adverse events after injection of polyacrylamide gel for soft-tissue augmentation. Correct application was essential to ensure a favorable result. For patients who desire facial soft-tissue augmentation, Aquamid is an excellent alternative to surgery.

The Effect of Centrifugal Forces on Viability of Adipocytes in Centrifuged Lipoaspirates

Standard protocols for autologous fat transfer involve centrifugation of the lipoaspirate for better separation. The effect of the centrifugal forces on cell viability and possible induction of apoptosis is discussed controversially in current literature. We have examined the vitality of adipocytes in lipoaspirates after centrifugation by 8 different accelerations up to 20.000g immediately after the respective centrifugation as well as 4 days later by staining. No significant alterations in the viability of differently centrifuged adipocytes were found. Cultivation of the samples after centrifugation revealed no apoptotic changes. Our results show that centrifugation, as a part of the protocol of lipofilling, has no effect on the survival rate of isolated adipocytes in the purified fat. In contrast, lipoaspirates centrifuged with higher accelerations seem to be better cleansed of oil and cell debris than samples treated with lower centrifugal forces.

Cortisol in severely burned patients: investigations on disturbance of the hypothalamic-pituitary-adrenal axis.

Thermal injuries of more than 20% of body surface area lead to conditions resembling a severe systemic inflammatory response syndrome, such as in septic shock. It has been shown that septic shock may lead to disturbances in cortisol metabolism and balance of the hypothalamic-pituitary-adrenal axis. To investigate whether such a disturbance also occurs in the very early stages of systemic inflammatory response syndrome in burned patients, we performed 20 corticotropin-releasing hormone tests on day 1 after admission to our unit. In 7 of 20 patients, a disturbance of cortisol secretion could be demonstrated. Four patients developed adrenal insufficiency. The correlation between the abbreviated burn severity index and the risk of developing adrenal insufficiency was significant (P = 0.008). We observed a higher mortality rate in adrenally insufficient patients; however, because of the small patient number, we were not able to prove this observation with a statistical significant correlation (P = 0.11). Our findings indicate that temporary adrenal insufficiency occurs in the early stages of severe injury. Further investigations will have to be performed to clarify whether such patients benefit from cortisol replacement.

Characterisation of angiogenetic growth factor production in adipose tissue-derived mesenchymal cells

Abstract Optimal vascularisation of the graft site is significant for improving the outcome of fat grafting. Adipose tissue, specifically the stromal vascular fraction (SVF), is known to regulate its own vascular network. In order to assess the production of angiogenetic growth factors, this study investigated the content of insulin growth factor (IGF), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), leptin, and metallothioneine-9 (MMP-9) in the SVF after incubation in differentiation or proliferation media. The SVF was isolated from human subcutaneous adipose tissue. Cells were either cultured in proliferation medium (PM) or in differentiation medium (DM). The samples were analysed for the respective factors using ELISA after 3 and 6 days. The GF levels showed a distinctive characteristic over time depending on the culture medium. IGF, PDGF, and MMP-9 levels decreased with PM and increased with DM. VEGF levels were increased in both media. Leptin showed a decrease in both media. The differentiation medium was associated with high inter-individual distribution in growth factor production except for PDGF and Leptin. In conclusion, incubation with differentiation medium produces a more reliable increase of selected growth factors than incubation with proliferation medium. Enrichment of fat grafts with growth factor-activated autologous SVF samples could help to enable better ingrowth of the transplanted tissue and a more stable outcome. The scattering of the results could explain the inter-individual differences regarding the outcome.

Defect classification and reconstruction algorithm for patients with tracheostomy using the tunneled supraclavicular artery island flap

PurposeFollowing long-term tracheostomy, reconstruction of the suprasternal notch and coverage of tracheocutaneous fistulas can be challenging. Often, aesthetic results are secondary to functional outcome. In this article, we propose a defect classification and a treatment algorithm using the tunneled supraclavicular artery island flap for functional and aesthetic reconstruction.MethodsTwelve patients requiring complete or partial closure of a tracheocutaneous fistula or soft tissue deficit reconstruction were treated with this pedicled flap. Support for the anterior tracheal wall was achieved by including fascia or bone into the flap.ResultsFunctional outcome was excellent, and suprasternal notch correction was achieved with good texture match. Donor sites could be closed primarily in every case. All flaps healed uneventfully, Long-term follow-up computed tomography scans demonstrated vital bone chips.ConclusionsThe proposed classification and treatment algorithm provides a structured approach to a successful surgical treatment of this complex condition.

The mobilisation of mononuclear cells and endothelial progenitor cells after burn injury in a porcine model.

BACKGROUND Mononuclear blood cells (MNCs) consist of heterogeneous cell populations, for example, CD34+ cells and endothelial progenitor cells (EPCs). EPCs are involved in vasculogenesis, but little is known about their role during burn trauma. AIM This study investigates the role of MNCs and their subpopulations during and after burn injury in an experimental porcine setting. METHODS Eighteen 8-week-old German land pigs were scalded by immersion in 70 degrees C hot water for 3 min, resulting in a 30% total body surface area (TBSA) full-thickness burn. Vascular endothelial growth factor (VEGF) serum concentrations and MNC, EPC and CD34+ cell counts were measured at eight different time points up to 48 h following trauma. RESULTS The experimental porcine setting made it possible to determine the cell counts of MNCs, EPCs and CD34+ cells directly during burn trauma, which has not been described before. The data revealed a fulminant drop in MNC and EPC during burn trauma, whereas the CD34+ cell fraction rose. Besides significant changes in the VEGF serum concentration, a correlation between VEGF and EPC was also observed. CONCLUSION The results show that MNCs and their subpopulations are significantly affected by burn trauma and underpin their potential diagnostic and therapeutic importance during and after burn injury.

Intra-alveolar IL-6 levels following burn and inhalation injury

Burn combined with inhalation injury is a major challenge and requires further study. Using a small-animal model, excretion of IL-6 was investigated during the first 6h after exposure of rats to wood/polyvinyl chloride smoke, with and without concomitant skin burn. In controls, respirator therapy alone was found to release IL-6 into the serum and the alveolar space. These levels of IL-6 were reduced when associated with either inhalation injury or burn, but were increased when the traumas were combined. Thus, during the first 6h of mechanical respiration the presence of burn or of inhalation injury seems to decrease IL-6 excretion, but a combination of these traumas reverses this effect.

A voxel based multiresolution technique for soft tissue deformation

Real time tissue deformation is an important aspect of interactive virtual reality (VR) environments such as medical trainers. Most approaches in deformable modelling use a fixed space discretization. A surgical trainer requires high plausibility of the deformations especially in the area close to the instrument. As the area of intervention is not known a priori, adaptive techniques have to be applied.We present an approach for real time deformation of soft tissue based on a regular FEM mesh of cube elements as opposed to a mesh of tetrahedral elements used by the majority of soft tissue simulators. A regular mesh structure simplifies the local refinement operation as the elements topology and stiffness are known implicitly. We propose an octree-based adaptive multiresolution extension of our basic approach.The volumetric representation of the deformed object is created automatically from medical images or by voxelization of a surface model. The resolution of the volumetric representation is independent of the surface geometry resolution. The surface is deformed according to the simulation performed on the underlying volumetric mesh.