The Use of the Symani Surgical System® in Emergency Hand Trauma Care.

Background: The use of robotic systems for microsurgery has gained popularity in recent years. Despite its drawbacks, such as increased learning time and lack of haptic feedback, robot-assisted microsurgery is beneficial for emergency care due to its reduced risk of tremor and fatigue. The Symani Surgical System® is 1 example of this advanced technology. The device offers a range of possibilities in the field of microsurgery by combining precision and dexterity, revolutionizing microsurgical procedures. This article explores the applications of the Symani in microsurgical procedures in emergency hand trauma care, highlighting its advantages and limitations. Material and Methods: We present the results of 62 anastomoses of blood vessels under .8 mm diameter after hand trauma. 31 anastomoses were conducted using the Symani Surgical System®, and the other 31 were done as a control group in hand-sewn technique. Study Sample: The patient characteristics, including sex, age, and risk factors, were matched. Results: We found no significant differences in the anastomosis surgery length when performed with the Symani (arterial 17.3 ± 1.9 min; venous 11.5 ± 1.3 min) vs the hand-sewn technique (arterial 16.1 ± 1.4 min; venous 10.2 ± 1.8 min). Additionally, the learning curve consistently decreased over time, with the 10th surgery taking 30% (arterial) less time. Conclusion: Our study indicates that robot-assisted microsurgery can help surgeons maintain a relaxed and focused state while producing results comparable to hand-sutured procedures in emergency care.

Organization of Hannover Skin Bank: Sterile culture and procurement protocols for viable cryopreserved allogeneic skin grafts of living donors.

Preserved allogeneic donor skin still represents one of the gold standard therapies in temporary wound coverage in severely burned patients or chronic wounds. Allogeneic skin grafts are currently commercially available as cryo- or glycerol-preserved allografts through skin tissue banks all over the world. Most of the skin tissue banks rely on human cadaveric skin donations. Due to the chronic shortage of human allogeneic transplants, such as skin, and increasing costs in the procurement of allografts from other skin tissue banks, Hannover Medical School has been building up its own skin tissue bank based on allogeneic skin grafts from living donors who underwent surgical treatment (i.e., body-contouring procedures, such as abdominioplasties). This article presents procedures and protocols for the procurement and processing of allogeneic skin grafts according to national legislation and European regulations and guidelines. Beside protocols, initial microbiological data regarding the sterility of the harvested grafts are presented. The results currently form the basis for further investigations as well as clinical applications. In summary, a microbiological testing and acceptance procedure is presented that ensures adequate patient safety and skin viability.

[Reduction of needlestick injuries by 48 % in 1 year : Effects of improvement of the safety concept according to the European Union Council directive 2010/32/EU at a large regional hospital]. / Reduktion von Nadelstichverletzungen um 48 % in einem Jahr : Auswirkungen einer Verbesserung des Sicherheitskonzeptes nach der EU-Direktive 2010/32/EU an einem großen regionalen Krankenhaus.

BACKGROUND: Needlestick injuries (NSI) are potentially infectious injuries from sharp or pointed medical instruments and through contact with blood on mucous membranes or nonintact skin. Although the European Union (EU) Council directive 2010/32/EU on the prevention of NSI was implemented in EU countries in 2013, information on the effectiveness of the measures is limited. OBJECTIVE: The aim of this study was to evaluate the effectiveness of a safety concept according to the EU Council Directive 2010/32/EU on prevention of NSI. MATERIAL AND METHODS: In 2016 the NSI safety concept at a large regional hospital was improved according to 2010/32/EU, specifically by an update of blood screening profiles and standard operating procedures (SOP), better dissemination of information to employees and complete conversion to safety cannulas and scalpels. The medical records of all NSIs from 2015-2017 were retrospectively anonymized and evaluated and a cost analysis was performed. RESULTS: The number of NSIs in 2017 was significantly reduced by 48.4% as compared to 2016 and NSIs with scalpels were completely prevented. The proportion of employees with NSIs who were adequately immunized against hepatitis B was significantly increased to 84.1% in 2017. Furthermore, identification of the index patient was significantly increased to 82.5% in 2017. The cost of avoiding NSIs increased by a total of 24.1% in 2017 as compared to 2015 before introduction of the safety concept. CONCLUSION: Implementation of the EU Council directive 2010/32/EU, resulted in an almost 50% reduction in NSIs over 1 year, including the complete prevention of NSIs due to scalpels. In addition, the anamnestic presence of immunization against hepatitis B and index patient identification were significantly increased.

Epidemiologic and Molecular Investigation of a MRSA Outbreak Caused by a Contaminated Bathtub for Carbon Dioxide Hydrotherapy and Review of the Literature.

METHODS: We conducted an outbreak investigation and performed a molecular typing of the outbreak strains with pulsed-field gel electrophoresis (PFGE). In addition, we reviewed PubMed and the Outbreak Database for MRSA outbreaks related to hydrotherapy or other bathing activities. RESULTS: Four patients acquired nosocomial MRSA during the 4-week outbreak period. Environmental sampling revealed the presence of MRSA in the bathtub used for hydrotherapy. The environmental and the patients' isolates showed an indistinguishable restriction pattern in the PFGE. Subsequent discontinuation of bathing stopped the outbreak. The literature search found 9 MRSA outbreak reports related to bathing activities or hydrotherapy. CONCLUSION: The epidemiologic outbreak investigation together with the molecular findings suggests monoclonal spread of MRSA due to surface contamination of the bathtub. After enhancing the disinfection and cleaning process accompanied by staff training with respect to hand hygiene, no further cases occurred. Standardized and best practice cleaning and disinfection protocols are crucial, especially in critical facilities such as hydrotherapy units. Regular environmental sampling is helpful to monitor these processes and to detect potential contamination.

Evaporative Water Loss in Superficial to Full Thickness Burns.

INTRODUCTION: Increased evaporative water loss (EWL) in burn patients leads to dehydration and hypothermia. Early clinical studies performed with outdated hygrometers suggested a 17 to 75 times increased EWL in burns with contradicting results for the different burn depths.Our study proposals were: (1) obtain reliable data of the EWL of all burn depths, (2) compare these results with findings from earlier studies, (3) evaluate the usefulness of the EWL in differentiating between superficial and deep partial thickness burns, (4) determine the effect of Biobrane on the EWL of superficial partial thickness burns in vivo, and (5) evaluate the effect of the sterile incision foil Opraflex on the EWL in split skin graft donor sites. METHODS: We measured the EWL of all burn depths in 28 patients under stable and recorded conditions regarding room temperature and humidity with a modern digital evaporimeter (Tewameter TM 300). For the first time in vivo, we also determined the effect of Biobrane on the EWL of burns and evaluated the EWL in split skin graft donor sites covered with Opraflex. RESULTS: The EWL in all burn depths was significantly increased (P < 0.001) compared with unburned skin. There was no significant difference (P > 0.05) in the EWL of superficial compared with deep partial thickness burns, whereas full thickness burns had a significantly lower EWL (P < 0.05) compared with superficial and deep partial thickness burns. Biobrane significantly reduced the EWL (P < 0.05) of superficial partial thickness burns. The EWL of Opraflex covered skin graft donor sites was significantly reduced compared with uncovered donor sites (P < 0.05). CONCLUSIONS: Our data suggest that the actual EWL in burns is approximately 3 times higher in full thickness burns and approximately 4 times higher in superficial and deep partial thickness burns compared with normal skin and therefore much lower than suggested previously.Because there was no significant difference in the EWL of superficial compared with deep partial thickness burns, the EWL cannot be used to differentiate between these burn depths.Biosynthetic wound dressings can significantly reduce the EWL of superficial partial thickness burns and sterile incision foil protects split skin graft donor sites from an increased EWL.

Reconstruction of an Extensive Segmental Radial Shaft Bone Defect by Vascularized 3D-Printed Graft Cage.

We report here a 46-year-old male patient with a 14 cm segmental bone defect of the radial shaft after third degree open infected fracture caused by a shrapnel injury. The patient underwent fixed-angle plate osteosynthesis and bone reconstruction of the radial shaft by a vascularized 3D-printed graft cage, including plastic coverage with a latissimus dorsi flap and an additional central vascular pedicle. Bony reconstruction of segmental defects still represents a major challenge in musculo-skeletal surgery. Thereby, 3D-printed scaffolds or graft cages display a new treatment option for bone restoration. As missing vascularization sets the limits for the treatment of large-volume bone defects by 3D-printed scaffolds, in the present case, we firstly describe the reconstruction of an extensive radial shaft bone defect by using a graft cage with additional vascularization.

Correlation between Bacterial Wound Colonization and Skin-Graft Loss in Burn Patients.

Loss of skin grafts can be a dangerous complication during the early postoperative course of patients with extensive burns. A major risk factor for impaired healing of grafts is local wound infection due to bacterial colonization. Burn wounds are particularly prone to bacterial colonization. In this retrospective cohort study, we analyzed correlations between bacteria isolates from burn wounds and loss of skin grafts after surgical treatment. A cohort of patients with burn wounds who received split-skin grafts for wound coverage was divided into groups with and without loss of skin grafts. Demographics, comorbidities, trauma characteristics and bacterial isolates from wound cultures were reviewed and compared. Bacterial colonization isolated from burn wounds upon hospital admission was found to be a significant predictor of skin-graft loss. Additionally, an Abbreviated Burn Severity Index greater 6 predicted graft loss. When comparing bacterial swab results from admission with isolates from revision surgery after graft loss, causative pathogens were found to have changed.

Major traumatic amputations and replantations of the upper extremity in Germany - National quality reports 2014-2018.

The treatment of traumatic major upper limb amputation is complex and of great urgency. Loss of time often represents a majorrestriction for replantation. Thus, logistical and infrastructural developments, such as the expansion of specialised hand trauma centres, are crucial for optimizing delivery of care. Surveillance represents the fundament for a proper, demand-adapted implementation of such therapeutical improvements. However, a comprehensive database for surveillance of these injuries does currently not exist in Germany or Europe. In this study quality reports of German hospitals from 2014 to 2018 were screened retrospectively for traumatic major upper extremity amputations and replantations. A total of 329 amputations and 87 replantations were recorded, accounting for an overall replantation rate (RR) of 26%. Most of the injuries affected the level of the wrist and forearm. Treatment of these injuries experienced an increasing centralisation to medical teaching facilities, which accounted for higher RRs compared with non-teaching facilities. The cumulatively most populous federal states handled most of the amputation injures in this five-year study period. Ratio calculations on the basis of population counts, however, revealed great discrepancies to these results, with Hamburg, Rhineland-Palatinate and Saarland accounting for the highest per capita incidences. In 2018 Germany was provided with 46 specialised hand trauma and replantation centres, which performed 45% of the replantations in that year, revealing a RR of 17%, compared to an overall RR of 14% in that year. Nevertheless, there might be potential for improvement in the geographical distribution of these specialised centres. The provision of highly specialised therapy in highly specialised centres for highly complex injuries is a future challenge in replantation surgery. This data is contributing to logistical improvements for a need-adapted expansion of these specialised hand trauma centres. The study demonstrates an approach of a standardised and comprehensive injury surveillance program based on national quality reports, while underlining the importance of such a national or rather European database for optimisations in medical care. Level of evidence IV.

An Identification and Characterization of the Axolotl (Ambystoma mexicanum, Amex) Telomerase Reverse Transcriptase (Amex TERT).

The Mexican axolotl is one of the few vertebrates that is able to replace its lost body parts during lifespan. Due to its remarkable regenerative abilities, the axolotl emerged as a model organism especially for limb regeneration. Telomeres and the telomerase enzyme are crucial for regeneration and protection against aging processes and degenerating diseases. Despite its relevance for regeneration, the axolotl telomerase and telomere length have not yet been investigated. Therefore, in the present paper, we reveal the sequence of the axolotl telomerase reverse transcriptase gene (Tert) and protein (TERT). Multiple sequence alignment (MSA) showed the known conserved RT- and TERT-specific motifs and residues found in other TERTs. In addition, we establish methods to determine the Tert expression (RT-PCR) and telomerase activity (Q-TRAP) of adult axolotl and blastema tissues. We found that both differentiated forelimb tissue and regenerating blastema tissue express Tert and show telomerase activity. Furthermore, blastema tissue appears to exhibit a higher Tert expression and telomerase activity. The presence of active telomerase in adult somatic cells is a decisive difference to somatic cells of non-regenerating vertebrates, such as humans. These findings indicate that telomere biology may play a key role in the regenerative abilities of cells.

Is there an association between comorbidities and the outcome of microvascular free tissue transfer?

The aim of this study was to evaluate the relevant conditions for safe free flap transfers. The authors retrospectively studied the data from 150 patients who received free flaps at a single institution. Many parameters were analyzed to reveal if there was a correlation with respect to surgical or medical complications. Regarding safety of free tissue transfer, we found a worse prognosis in flaps where a revision of the microanastomosis had to be performed. Platelet count and leukocyte count had an impact on the prognosis. Patients older than 60 years did not have an increased rate of surgical complications. Apart from active osteomyelitis, the presence of comorbid conditions did not significantly impair the outcome of flap transfer, although smoking and diabetes correlated with minor surgical complications like wound breakdown or hematoma, respectively. Besides one case of lethal heart failure of an octogenarian patient, no severe medical complications occurred in this series of patients. Microvascular free tissue transfer is not significantly impaired by age and most comorbidities. Osteomyelitis as well as elevated leukocytes and lowered platelets may increase the complication rate and worsen the surgical prognosis. Smoking and diabetes might prolong the hospital course of the patients.

Comment on: "Thumb carpometacarpal joint osteoarthritis: Is there a role for denervation? A systematic review".

We read with great interest the recent systematic review by Teo I. and Riley N. on denervation in thumb carpometacarpal joint osteoarthritis. Undoubtedly, denervation of the first carpometacarpal (CMC-1) joint does represent a promising surgical treatment alternative for patients suffering from persistent CMC-1-joint osteoarthritis. A surgical standard, however, has not yet been implemented, as technical approach and indication of this procedure still show great variances. In order to contribute to an evidence-based standardization of CMC-1-joint denervation, we would like to share our considerations, approaches and anatomical findings in this comment.

Treatment of hand infections using WALANT -when the anesthesiologist is not available: A retrospective cohort study.

BACKROUND: The aim of this study was to determine, if Wide Awake Local Anesthesia No Tourniquet (WALANT) can be used as an alternative method of providing anesthesia in management of deep infections of the hand. Since the advent of WALANT in 2003, infections of the hand have been regarded as a contraindication to its use. Occasional shortage of anesthesiologic manpower, especially during busy call hours and the current COVID-19 pandemic can lead to delay of treatment where urgent surgery is needed, to prevent progress of an infection, that can result in severe morbidity. METHODS: In the period from 2015 to 2020, 16 patients with various infections of the hand underwent 17 operations using WALANT in a Hand Trauma and Replantation Center (HTRC) in Germany. Retrospective cohort analysis of their operation reports, with emphasis on location of infection, time and duration of the operation, intraoperative incidents and complications were carried out. We also evaluated the need for revision surgery or necessity to convert to general anesthesia and factors causing delay till the time of surgery. RESULTS: No case of inadequate analgesia, the need to convert to general anesthesia, ischemic events or cardiovascular complications with the use of the WALANT solution containing adrenaline and lidocaine in the treatment of deep tissue infections.The highest priority of limb preservation was ensured as no patient progressed to amputation of a digit or the hand. There was a statistically significant difference (p ≤ 0.01) in delay from the time of admission until surgery of up to 9h24 m (SD±3h34 m) during the week and 4h10 m (SD±2h28 m) during the weekend. CONCLUSION: The status of infection as an absolute contraindication to the use of WALANT should be revised. Especially when human resources are limited, WALANT is an adequate technique to enable quick anesthesia for urgent treatment to prevent progression of hand infections.

Hot Bathtub, Cold Consequences-Misleading Wounds After Scald Injuries: A Retrospective Analysis.

Scalds in the elderly are frequently associated with the use of a bathtub and a disturbed consciousness. Therefore, the total burn surface area is often high. The initial clinical presentation displays a stark erythema of the skin, which frequently does not represent the true depth. The aim of this study was to characterize and assess medical features and outcome of scalds sustained in the bathtub. We conducted a retrospective study at a burn intensive care unit (BICU) between 2011 and 2018. Medical features as well as the treatment in these patients were statistically analyzed. We identified 16 patients and divided them into two groups regarding survival and lethality. The mean total burn surface area was 37.50 ± 19.47%. In 81.25% of the patients, we found a previous history of neurological or psychiatric disorders. Dementia and alcohol abuse were the most common triggers for the trauma. The statistical analysis showed a significant difference for the ABSI-score and the presence of multi organ failure (P-value .0462, respectively, .0004). Erythematous skin areas tended to progress into full thickness burns. We, therefore, coined the term "lobster redness" for these regions. Scalds sustained in the bathtub are devastating injuries. Initial assessment can be misleading and might delay early necrectomy. The wounds request even more attention, if the injuries occurred due to unconsciousness because of the longer exposure to heat. Early necrectomy should be considered. A biopsy with histological workup can be useful. Furthermore, we recommend special safety precautions for neurologically and psychiatrically affected patients.

Reconstruction of Basic Hand Function by a Free Osteocutaneous Spare-Part Flap From the Lower Leg After Septicemia: A Case Report.

Background: Spare-part surgery is widely accepted and offers an option in extremely traumatized patients for reconstructive maneuvers. Standardized techniques are lacking, and the therapy needs to fit the patient's clinic. Materials and Methods: In a woman with necrosis of almost all extremities due to septic infection, we used the lower leg as a free osteocutaneous flap to reconstruct a basic hand function after amputation. The fibula segment was buried alongside the remaining first metacarpal bone. On the hand stump, 2 short metacarpals were lengthened using the remaining 2 metacarpals as osteovascular on-top plasties. The flap was microsurgically anastomosed end-to-side to the ulnar artery. After 3 months, the buried fibula was trimmed to the necessary thumb length and fixed to the local metacarpal I stump. Secondary procedures were performed to deepen the first web space. Results: The patient is now able to manage her daily life. Also, she is able to put on her prosthesis on both legs and walk without aids. Conclusions: To our knowledge, this is the first description of successful microvascular transfer of an osteocutaneous free flap from an amputated lower leg of this size and could present a valuable technique for other cases.

Spread of Hand Infection According to the Site of Entry and Its Impact on Treatment Decisions.

Background: Hand infections can spread quickly and destroy functional structures. Early diagnosis and adequate therapy can prevent severe morbidities. The aim of this study was to evaluate systematically the spread of hand infections according to injury mechanism, pathogens, and entry site. Methods: The data and medical records of 425 patients were collected and analyzed retrospectively. Results: The entry site had a significant influence on the severity of hand infections. Especially finger lesions led to severe infections. Furthermore, a high C-reactive protein (CRP) concentration correlated with more involved compartments of the hand. Bacterial counts also correlated with the number of compartments involved. Conclusions: Compared with known factors for the severity of hand infections finger lesions lead to especially severe infections and should not be underestimated. If there is a higher CRP concentration or more than one bacterial species isolated, compartments adjacent to the site of injury should be checked intra-operatively.

Trauma mechanisms, patterns of injury, and outcomes in a retrospective study of 71 burns from civil gas explosions.

BACKGROUND: Although explosion injuries caused by terror attacks or in war are evaluated in many studies, limited information about civil explosion injuries can be found in the literature. METHODS: In a retrospective study of 71 civil gas explosion injuries treated in a single burn center during a 16-year period, we evaluated trauma mechanisms, patterns of injury, and clinical outcome. RESULTS: More than 50% of all gas explosions injuries occurred in private households. The mortality correlated significantly with higher burned total body surface area (TBSA), higher abbreviated burn severity index (ABSI) score, accompanying inhalation injuries, and lung contusions. Although mean ABSI score and burned TBSA were similar in men and women (6 vs. 7 and 22% vs. 21%), the female mortality from gas explosions was noticeably higher, albeit not statistically significant due to small patient numbers (32% vs. 17%). Although mean burned TBSA, ABSI scores, and intensive care unit lengths of stay in patients with burns from gas explosions were comparable and not significantly different compared with all burn patients treated in our burn center (TBSA: 22% vs. 17%; ABSI: 6 vs. 6; and intensive care unit lengths of stay: 12 vs. 11 days), the mortality from gas explosions was significantly higher (21% vs. 12%, p = 0.04). CONCLUSIONS: The mortality from gas explosion-related burns correlated significantly with burned TBSA, ABSI score, accompanying inhalation injuries, and lung contusions. Despite comparable ABSI scores, the mortality from gas explosion-related burns was significantly higher than the mortality for all burn victims.

A new technique for gluteal lifting using deepithelialized dermal flaps.

BACKGROUND: Gluteal ptosis may result from sagging of redundant skin and fat below the infragluteal fold. The correction of gluteal ptosis and the definition of gluteal prominence can be obtained by several gluteal lifting techniques. We present a new technique to correct gluteal ptosis using deepithelialized dermal flaps. METHODS: Eight female patients (39 + or - 4 years old) with gluteal ptosis were included in the study. Six patients had been previously operated on elsewhere (liposuction, body lift). Gluteal lifting is performed using a crescent-shaped deepithelialized flap. The cranial two-thirds of the flap is sutured to the gluteal fascia, thus creating the new gluteal curvature and the position of the new infragluteal fold. The lower third of the flap is then sutured back toward the two-thirds flap within the first suture line, resulting in a doubling of the deepithelialized area. RESULTS: The mean operating time was 100 + or - 20 min (range = 75-110 min). There were no complications in the study group. An analysis of postoperative results revealed a very good aesthetic aspect in all patients. All patients showed an improved definition of the infragluteal fold, with a symmetric shape of the gluteal region. All patients judged the outcome as very good. CONCLUSION: The use of a deepithelialized double dermal flap is a safe and new way to obtain excellent results in rejuvenation of the gluteal region. Our technique allows for the creation of a stable and long-lasting infragluteal fold with an aesthetic buttock curvature and a defined border to the thigh region.

Mannose-binding lectin (MBL) and the lectin complement pathway play a role in cutaneous ischemia and reperfusion injury.

OBJECTIVES: Cutaneous ischemia/reperfusion (CI/R) injury has shown to play a significant role in chronic wounds such as decubitus ulcers, diabetic foot ulcers, atherosclerotic lesions, and venous stasis wounds. CI/R also plays a role in free tissue transfer in reconstructive microsurgery and has been linked to clinical burn-depth progression after thermal injury. While the role of the complement system has been elucidated in multiple organ systems, evidence is lacking with respect to its role in the skin. Therefore, we evaluated the role of the complement system in CI/R injury. METHODS: Using a single pedicle skin flap mouse model of acute CI/R, we performed CI/R in wild-type (WT) mice and complement knock out (KO) mice, deficient in either C1q (C1q KO; classical pathway inhibition), mannose-binding lectin (MBL null; lectin pathway inhibition) or factor B (H2Bf KO; alternative pathway inhibition). Following 10 h ischemia and 7 days reperfusion, mice were sacrificed, flaps harvested and flap viability assessed via Image J software. The flap necrotic area was expressed as % total flap area. In another group, mice were sacrificed following CI/R with 10 h ischemia and 48 h reperfusion. Two cranial skin flap samples were taken for gene expression analysis of IL1b, IL6, TNFα, ICAM1, VCAM1, IL10, IL13 using real-time polymerase chain reaction (RT-PCR). RESULTS: Following CI/R, MBL null mice had a statistically significant smaller %necrotic flap area compared to WT mice (10.6 vs. 43.1%; p<0.05) suggesting protection from CI/R. A significantly reduced mean %necrotic flap area was not seen in either C1q KO or H2Bf KO mice relative to WT (22.9 and 31.3 vs. 43.1%; p=0.08 and p=0.244, respectively). There were no statistically significant differences between groups for markers of inflammation (TNFα, ICAM1, VCAM1, IL1b, IL6). In contrast, mRNA levels of IL10, a regulator of inflammation, were significantly increased in the MBL null group (p=0.047). CONCLUSIONS: We demonstrated for the first time a significant role of MBL and the lectin complement pathway in ischemia/reperfusion injury of the skin and a potential role for IL10 in attenuating CI/R injury, as IL10 levels were significantly increased in the tissue from the CI/R-protected MBL null group.

Formation of three-dimensional tubular endothelial cell networks under defined serum-free cell culture conditions in human collagen hydrogels.

Implementation of tubular endothelial cell networks is a prerequisite for 3D tissue engineering of constructs with clinically relevant size as nourishment of cells is challenged by the diffusion limit. In vitro generation of 3D networks is often achieved under conditions using serum containing cell culture medium and/or animal derived matrices. Here, 3D endothelial cell networks were generated by using human umbilical vein endothelial cells (HUVECs) in combination with human adipose tissue derived stromal cells (hASCs) employing human collagen I as hydrogel and decellularized porcine small intestinal submucosa as starter matrix. Matrigel/rat tail collagen I hydrogel was used as control. Resulting constructs were cultivated either in serum-free medium or in endothelial growth medium-2 serving as control. Endothelial cell networks were quantified, tested for lumen formation, and interaction of HUVECs and hASCs. Tube diameter was slightly larger in constructs containing human collagen I compared to Matrigel/rat tail collagen I constructs under serum-free conditions. All other network parameters were mostly similar. Thereby, the feasibility of generating 3D endothelial cell networks under serum-free culture conditions in human collagen I as hydrogel was demonstrated. In summary, the presented achievements pave the way for the generation of clinical applicable constructs.