Aesthetic Surgery Fellowship at Akademikliniken Stockholm: Survey among Graduates.

BACKGROUND: Aesthetic Surgery is one of the most competitive fields of plastic surgery. Although there is a certain demand for highly educated surgeons in this field, training in cosmetic procedures remains challenging. Akademikliniken Stockholm offers a highly appreciated fellowship program for aesthetic plastic surgeons and trained more than 200 surgeons from all over the world. OBJECTIVES: The aim of the present work was to provide insights into this fellowship program, analyze what graduates have learned and if this had implications on their further professional orientation. METHODS: Participants of the Akademikliniken fellowship program, who graduated between 10/2008 and 10/2018 (n = 66) were invited to take part in an online survey which included 30 questions about general demographics and about experience before, during and after the fellowship. RESULTS: Thirty-four graduates participated in the survey (52%). Twenty-four graduates (71%) had been already specialists in plastic surgery before commencing the fellowship program. Mean length of fellowship was 7 months (range 3-24months). Numbers of aesthetic procedures performed by the applicants significantly increased after the fellowship, and moreover, the scope of daily clinical practice shifted toward aesthetics in almost all applicants. CONCLUSIONS: A well-designed dedicated aesthetic surgery fellowship can improve the lack of training, aesthetic surgeons have during their residency. Graduates of our fellowship program reported great improvements in confidence in performing aesthetic procedures and a benefit for their future career. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Evaluation of Different Breast Implant Shapes in the Same Patient: Is There Really a Difference between Round and Anatomical Implants?

Background: The choice of the right implant shape is one of the most frequent debates in cosmetic breast augmentation. In current literature, the question of whether there is a difference in the appearance of different implant shapes is still an argument of highly controversial discussion. The aim of the present work was, therefore, to analyze whether any difference exists in terms of aesthetic outcome between round and anatomical implants, and if they can be distinguished from each other in a like for like swap, making sure the evaluation was made in exactly similar conditions. Methods: Fourteen consecutive patients who underwent aesthetic breast augmentations received primarily an implant of a given volume, projection, and shape (round or anatomical) and then decided to undergo implant replacement to a different shape but maintaining the same volume and projection. At 12-months follow-up, standardized photographs were taken, blinded and randomized. They were evaluated by 10 plastic surgeons and 10 nurses. Results: All 20 observers could distinguish between round and anatomical shape in all 14 cases (100%), which was highly significant (P < 0.0001) for each observer. Conclusions: The present data indicate that there is a clear difference between anatomical and round-shaped implants in terms of aesthetic appearance, when a comparison is properly performed. With the use of both round and anatomical implant shapes, aesthetically appealing results can be achieved in cosmetic breast augmentation. The right implant choice must be made, based on patients' anatomy and desires.

Pharmacological elevation of sphingosine-1-phosphate by S1P lyase inhibition accelerates bone regeneration after post-traumatic osteomyelitis.

Posttraumatic osteomyelitis and the ensuing bone defects are a debilitating complication after open fractures with little therapeutic options. We have recently identified potent osteoanabolic effects of sphingosine-1-phosphate (S1P) signalling and have now tested whether it may beneficially affect bone regeneration after infection. We employed pharmacological S1P lyase inhibition by 4-deoxypyrodoxin (DOP) to raise S1P levels in vivo in an unicortical long bone defect model of posttraumatic osteomyelitis in mice. In a translational approach, human bone specimens of clinical osteomyelitis patients were treated in organ culture in vitro with DOP. Bone regeneration was assessed by µCT, histomorphometry, immunohistology and gene expression analysis. The role of S1P receptors was addressed using S1PR3 deficient mice. Here, we present data that DOP treatment markedly enhanced osteogenesis in posttraumatic osteomyelitis. This was accompanied by greatly improved osteoblastogenesis and enhanced angiogenesis in the callus accompanied by osteoclast-mediated bone remodelling. We also identified the target of increased S1P to be the S1PR3 as S1PR3-/- mice showed no improvement of bone regeneration by DOP. In the human bone explants, bone mass significantly increased along with enhanced osteoblastogenesis and angiogenesis. Our data suggest that enhancement of S1P/S1PR3 signalling may be a promising therapeutic target for bone regeneration in posttraumatic osteomyelitis.

Implicit Metaethical Intuitions: Validating and Employing a New IAT Procedure.

Philosophical arguments often assume that the folk tends towards moral objectivism. Although recent psychological studies have indicated that lay persons' attitudes to morality are best characterized in terms of non-objectivism-leaning pluralism, it has been maintained that the folk may be committed to moral objectivism implicitly. Since the studies conducted so far almost exclusively assessed subjects' metaethical attitudes via explicit cognitions, the strength of this rebuttal remains unclear. The current study attempts to test the folk's implicit metaethical commitments. We present results of a newly developed Implicit Association Test (IAT) for metaethical attitudes which indicate that the folk generally tend towards moral non-objectivism on the implicit level as well. We discuss implications of this finding for the philosophical debate.

Anatomical Variations of the Pectoralis Muscle and Its Importance for Breast Implant Surgery.

In breast augmentation, during submuscular or dual plane dissection, anatomical variations of the inferior and costal origin of the pectoralis major muscle (PMM) play a key role to ensure optimal implant coverage. Especially, a short and narrow muscle or surgical release along the sternum increases the risk of irregularities and animation deformities of the implant. Methods: In 84 consecutive aesthetic breast augmentations intraoperatively, measurement of PMM dimensions was performed bilaterally. These PMM measurements were then correlated with the preoperative breast width, the inframammary fold, and the placement of the implant's lower pole. Results: One hundred sixty-eight PMMs of 84 patients were dissected with a dual plane II or III technique for primary aesthetic breast augmentation. In 88% of breasts, the calculated implants' lower pole was below the inferiomedial origin of the pectoralis muscle. In 10% of patients, a separation (more than 1 cm wide and 2 cm wide) in the inferior-medial origin of the PMM was noted. An asymmetry more than 0.5 cm in length between the left and right pectoralis major was noted in 36% of patients. Conclusions: In this series, the anatomy of the PMM demonstrates a substantial variability in width and length and a considerable asymmetry in its dimensions. These findings emphasize the importance of good access and visualization of the origin of the PMM fibers before its division.

Standardized Quantitative Sensory Testing to Assess Insufficient Recovery of Touch Discrimination in Free Flap Surgery.

BACKGROUND: With major advances in microsurgical techniques, free tissue transfer has become a widely adopted approach to treat complex soft-tissue defects. However, sensory recovery is poor, leaving the anesthetic skin prone to injuries. METHODS: Twenty-eight patients with 22 anterior lateral thigh flaps and six latissimus dorsi flaps on their extremities participated in the study. Quantitative sensory testing and two-point discrimination was performed in three test areas and one control on the contralateral unaffected extremity. Physical disability, mental health, quality of life, and characteristics of pain were assessed by the painDetect, Disabilities of the Arm, Shoulder, and Hand, Lower Extremity Functional Scale, and 12-Item Short Form questionnaires, respectively. RESULTS: Somatosensory profiles of all flaps were characterized by an overall loss of nerve function. Small-fiber function was mostly recovered, whereas large-fiber function, and thus touch discrimination, was severely impaired. Mechanical detection thresholds improved over time and from center to the periphery. Reported pain was mild to moderate and correlated with decreased physical function. CONCLUSIONS: Standardized quantitative sensory testing provides a useful tool kit to assess the sensory regeneration after surgical treatment of soft-tissue defects. After free tissue transfer, small-fiber function recovers with nerve ingrowth in a centripetal direction from the flap margins to the center, likely by way of collateral axonal sprouting from the undamaged nerves surrounding the flap. Myelinated fibers recover slowly and inefficiently. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Postoperative Remote Ischemic Conditioning (RIC) significantly improves entire flap microcirculation beyond 4 hours.

OBJECTIVE: Free flap transfer is a safe and reliable technique for soft tissue reconstruction. However, impaired flap perfusion with consecutive microcirculatory failure leading to partial or total flap failure remains a clinically relevant problem. Remote ischemic conditioning (RIC) has been shown to improve microcirculation in adipo-cutaneous tissues in healthy humans as well as in free flaps. Yet, little is known about its effects on different perfusion zones in free flaps and the duration of these effects. METHODS: Twenty-five patients with free perforator-based adipo-cutaneous flap transfer were included in the study. RIC (3 cycles: 10/10 min ischemia/reperfusion) was applied via an inflatable tourniquet placed on the upper arm. Continuous measurement of flaps' microcirculation on postoperative day (POD) 1, 3, and 5 was performed by utilizing an O2C device ("Oxygen-to-see" ©LEA Medizintechnik Germany) during RIC and for the following 4 h. Probes were located both in the flaps' center and on its distal edge. RESULTS: Twenty patients were included in the final analysis. RIC significantly improved flaps' blood flow (BF) by a max. of + 19.6% and oxygen saturation of + 15.7%. Changes affected the entire flap, without significant difference between zones. The increase in flap perfusion could be observed for at least 4 h after the completion of RIC. CONCLUSION: Postoperative application of RIC might serve as an additional treatment to enhance whole flap perfusion and prevent microcirculatory disorders, therefore reducing the risk for potential tissue necrosis, especially in the distal parts of the flaps.

Closed-Incision Negative-Pressure Wound Therapy after Resection of Soft-Tissue Tumors Reduces Wound Complications: Results of a Randomized Trial.

BACKGROUND: Wound healing after resection of large soft-tissue tumors is often impaired by large dead space and fluid collection. Recently, the authors were able to show an association of wound complications with worse oncologic outcome in soft-tissue sarcomas. The aim of the study was to examine the value of closed-incision negative pressure wound therapy on postoperative wound drainage and wound complications after soft-tissue tumor resection. METHODS: Patients for whom resection is planned of a soft-tissue tumor larger than 10 cm in diameter of the extremities or the trunk were allocated randomly to one of two groups. After wound closure, patients in the study group received closed-incision negative-pressure wound therapy for a duration of 5 days, whereas those in the control group received regular dressings. The amount of drainage fluid, course of wound healing, length of hospital stay, and wound edge perfusion at postoperative day 5 measured by white-light infrared spectroscopy were compared. RESULTS: Sixty patients could be included in the study with even distribution to both study arms, meeting the goal. The postoperative course of wound drainage volume was significantly lower in the study group, and hospital stay was significantly shorter, with 9.1 ± 3.8 days versus 13.9 ± 11.8 days. The occurrence of wound complications was significantly lower in the study group on time-to-event analysis (one versus six). Tissue spectroscopy revealed a significantly higher oxygen saturation increase in the wound edge for the study group versus the control group. CONCLUSION: Closed-incision negative-pressure wound therapy should be considered for patients undergoing resection of large soft-tissue tumors. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Maggot Extract Interrupts Bacterial Biofilm Formation and Maturation in Combination with Antibiotics by Reducing the Expression of Virulence Genes.

Biofilms are aggregates of bacteria encased in an extracellular polymer matrix that acts as a diffusion barrier protecting the microbial community. Bacterial communication occurs by small signaling molecules called quorum sensing (QS) factors, which are involved in the activation of virulence genes and formation of biofilms. Larvae of the green bottle blowfly Lucilia sericata remove necrotic tissue by mechanical action (debridement) and proteolytic digestion. We produced a freeze-dried storable powder from larval extract and investigated its therapeutic effect on biofilms. Larval extract in concentrations of 6 and 12 mg/mL in combination with 0.5% antibiotics (≙50 U/mL penicillin and 50 µg/mL streptomycin) diminished free-floating (planktonic) Pseudomonas aeruginosa maintenance, while it showed no effect on Staphylococcus aureus and was not toxic to dermal cells. We established an ex vivo human dermal wound model. Larval extract in concentrations of 24 and 75 mg/mL in the presence of antibiotics (0.5%) significantly destroyed the biofilm stability of both P. aeruginosa and S. aureus biofilms. Furthermore, SEM analyses revealed crack and gap formations on P. aeruginosa. biofilm surface and decreased expression of P. aeruginosa biofilm maturation and virulence genes (lasR, rhlR and rhlA) was observed after treatment by larval extract in combination with antibiotics.

Hierarchical Ceramic Coating Reduces Adherence of Cells, Blood, Bacteria, and Tissue on Titanium Microsurgical Instruments.

BACKGROUND: Progress in the field of microsurgery allows more detailed reconstructions of the smallest tissue structures. The applied instruments are left with biological residues after coming into contact with body fluids or tissue, leading to compromised surgical precision. Designing of residue-free innovative instruments would reduce the necessity of subsidiary practices and would improve the surgical precision. METHODS: We designed a ceramic coating (Lotus ceramic coating system 26-LCC-26) that exhibits self-cleaning surface properties on coated titanium specimens. A titanium surface was modified by blasting technology and electropolishing, followed by applying a high-performance ceramic and sol-gel finish layer. The physical surface characterization was performed by scanning electron microscopy and measuring the contact angle. The cell-repellent properties and cytotoxicity were investigated using live-dead staining, BrdU, and lactate dehydrogenase assay. Furthermore, bacterial and fluid-adhesion tests were performed. Finally, blood compatibility was analyzed according to DIN ISO 10993. RESULTS: The composite system LCC-26 increased the hydrophobic character of the titanium surface (the water contact angle of 74.9 degrees was compared with 62.7 degrees of the uncoated native titanium; p < 0.01) and led to the fluid and cell-repellent properties shown by the reduction in fibroblast adherence by ∼50.7% (p < 0.05), the reduction in Staphylococcus aureus pathogen colonization by 74.1% (p < 0.001), and the decrease in erythrocyte adherence by 62.9% (p < 0.01). Furthermore, the LCC-26 coated titanium microforceps dipped in human whole blood exhibited blood-repellent character (reduction in blood adherence by 46.1%; p < 0.05). Additionally, cyto- and hemocompatibility was guaranteed in direct and indirect tests. CONCLUSION: Titanium surface modification on surgical instruments exhibits cell, bacteria, and blood-repellent properties with a full guarantee of cyto- and hemocompatibility. Thus, innovatively coated instruments could contribute to increased precision during microsurgical interventions and optimized medical operation routines in the future.

TGF-beta pathway inhibition as the therapeutic acceleration of diabetic bone regeneration.

Bone regeneration and fracture healing are impaired in diabetic patients due to defective functions of associated cells. Thus, the search for molecular causes and new treatment strategies are of particular clinical relevance. We investigated the gene expression profile of bones from type 2 diabetic (db- /db- ) mice and wild-type (wt) mice by comparative microarray analyses before and after placing tibial defects and examined the expression of several osteogenesis- and osteoclastogenesis-related markers by quantitative real-time polymerase chain reaction. In regenerating wt bones, pathways related to, for example, inhibition of matrix metalloproteases were activated, whereas in db- /db- bones activation of pathways related to, for example, osteoarthritis, transforming growth factor-beta (Tgfb), or hypoxia-inducible factor 1a were detected during regeneration. We defined the Tgfb pathway as a potential therapeutic target and locally applied a single dose (0.5 µg) of the Tgfb 1, 2, and 3 neutralizing antibody 1D11 on tibial defects in db- /db- mice (n = 7). Seven days postoperation, histological and immunohistochemical stainings were performed. Decreased bone regeneration, osteogenic differentiation, osteoclast invasion, and angiogenesis in db- /db- mice were significantly restored by local 1D11 application in comparison to the phosphate-buffered saline controls. Thus, local treatment of db- /db- bony defects with Tgfb neutralizing antibody 1D11 might be considered a good candidate for the successful acceleration of bone regeneration.

Antibiotic prophylaxis for prevention of wound infections after soft tissue sarcoma resection: A retrospective cohort study.

BACKGROUND AND OBJECTIVES: The use of antibiotic prophylaxis for soft tissue sarcoma resection varies widely while little evidence on this topic exists. The aim of this study was to determine the impact of antibiotic prophylaxis on the occurrence of wound infections. METHODS: A single institutional retrospective cohort study was performed on patients who underwent truncal or extremity soft tissue sarcoma resection. The use of antibiotic prophylaxis was assessed and univariate and multivariate analysis of predictors of wound infections was performed. RESULTS: Nine hundred and fifty-eight patients could be included. Thirty-two percent of patients had no antibiotic prophylaxis, 44% of patients received single-shot prophylaxis, and 24% of patients received single-shot plus continued antibiotic treatment. Wound infections occurred in 140 patients (15%). Independent risk factors for wound infections upon multivariate analysis were obesity, high American Society of Anesthesiologists (ASA) status, high tumor size and grade, operation time over 120 minutes, and other complications. Antibiotic prophylaxis could not be identified as a protective factor in univariate or multivariate analysis. CONCLUSIONS: A favorable effect of antibiotic prophylaxis on the occurrence of wound infections could not be observed. Although more studies on this subject are needed, our data do not support the general use of antibiotic prophylaxis for soft tissue sarcoma resection.

Wound complications are a predictor of worse oncologic outcome in extremity soft tissue sarcomas.

BACKGROUND: In various oncological conditions, complications correlate with diminished prognosis, however literature on soft tissue sarcomas is limited and inconclusive. The aim of this study was to assess risk factors and the oncologic impact of wound complications in primary extremity soft-tissue sarcomas. METHODS: Patients with primary extremity soft tissue sarcomas without dissemination and with clear surgical margins (R0) were analyzed. Groups with and without wound complications were compared by univariate and multivariable analysis to identify risk factors. Uni- and multivariable analysis of factors associated with local recurrence free survival (LRFS), metastasis free survival (MFS) and disease specific survival (DSS) were performed. RESULTS: 682 patients were included in the study, wound complications occurred in 94 patients (13.7%) within 90 days. Age, ASA-stage, high tumor size and grade, tumor location in the foot, neoadjuvant radiation therapy and operation time represented independent risk factors for wound complications. Patients with wound complications had a significantly worse estimated 5-year LRFS of 49.4 ± 6% versus 78.3 ± 2.1% and 5-year DSS of 77.9 ± 5.4% versus 89.1 ± 1.6%. Wound complications could be identified as an independent risk factor for worse LRFS (HR 2.68[CI 1.83-3.93], p < 0.001) and DSS (HR 1.79[CI 1.01-3.16], p = 0.046). CONCLUSION: Wound complications after soft tissue sarcomas of the extremities are associated with worse local oncological outcome and survival. Patients with high risk of wound complications should be identified and strategies implemented to reduce surgical complications and possibly improve oncologic prognosis.

Enzymatic debridement of hands with deep burns: a single center experience in the treatment of 52 hands.

Background: Bromelain-based enzymatic debridement has been introduced as an alternative to surgical excision in deep partial thickness and full thickness burns. We aimed to analyze effectiveness and predictors of spontaneous epithelialization after enzymatic debridement of deep hand burns.Methods: All patients who received enzymatic debridement for deep partial thickness or full thickness burns of the hands at our institution in the last 5 years were identified. Demographic, clinical and outcome data were collected and analyzed. For patients with deep partial thickness burns, Kaplan-Meier log-rank and subsequent multivariate Cox-regression analysis were performed to identify predictors of spontaneous epithelialization.Results: 44 patients and 52 hands were treated in the observation period. Among these, 14 had full thickness burns and received split thickness skin grafts. In the 38 hands with deep partial thickness burns, predictors of 28-day epithelialization were total burn extent and mechanism of burn injury. During the first 3 years, 8 out of 13 treated deep partial thickness burns received split thickness skin grafts after a median of 3 days. The following 3 years, 5 out of 25 deep partial thickness burns received surgery after a median of 14 days.Conclusions: Enzymatic debridement is a useful tool in the treatment of burned hands but the decision-making and correct timing of operative intervention in deep partial thickness burns after debridement requires experience. In our cohort, spontaneous healing of deep partial thickness burns was best in patients with contact burns and less than 15% burn TBSA.

Predictors of oncologic outcome in patients with and without flap reconstruction after extremity and truncal soft tissue sarcomas.

BACKGROUND: Soft tissue sarcomas (STS) of the extremities or trunk often require plastic reconstructive transfer of vital tissue for wound closure after resection. Literature on the oncologic outcome of patients receiving flap closure in comparison with patients receiving primary wound closure is very limited. METHODS: Patients who underwent resection of a primary extremity or truncal STS without dissemination at our institution between January 2000 until December 2015 were eligible for the study. Patients were divided into two groups based on type of soft tissue closure (primary or flap) while patients receiving skin grafting were excluded. Characteristics, oncologic outcome and prognostic factors of both groups were compared. RESULTS: 781 patients could be included, of these 200 had received flap closure and 581 primary wound closure. Tumors receiving flap closure were significantly smaller but were located in distal extremities and showed a trend towards prior neoadjuvant radiotherapy. Incidence of wound and general complications was similar in both groups. 5-year local recurrence free survival (LRFS, 71% vs. 69%) and 5-year disease specific survival (DSS, 84% vs. 88%) did not differ significantly between patients with primary closure and flap closure. Most important predictors in both groups were tumor size and grading with no major differences in analysis of predictors for both endpoints. CONCLUSION: Plastic reconstructive surgery plays an important role in limb-conserving STS treatment. Complication rates of patients with flap coverage are not higher than of patients with primary wound closure and oncologic outcome is similar with no major differences in predictors of LRFS and DSS.

Inflammatory processes and elevated osteoclast activity chaperon atrophic non-union establishment in a murine model.

BACKGROUND: Delayed bone healing, especially in long bones poses one of the biggest problems in orthopeadic and reconstructive surgery and causes tremendous costs every year. There is a need for exploring the causes in order to find an adequate therapy. Earlier investigations of human scaphoid non-union revealed an elevated osteoclast activity, accompanied by upregulated levels of TGF-beta and RANKL. Interestingly, scaphoid non-union seemed to be well vascularized. METHODS: In the current study, we used a murine femur-defect model to study atrophic non unions over a time-course of 10 weeks. Different time points were chosen, to gather insights into the dynamic processes of non-union establishment. RESULTS: Histological analyses as well as western blots and qRT-PCR indicated enhanced osteoclast activity throughout the observation period, paralleled by elevated levels of TGF-beta, TNF-alpha, MMP9, MMP13 and RANKL, especially during the early phases of non-union establishment. Interestingly, elevated levels of these mediators decreased markedly over a period of 10 weeks, as inflammatory reaction during non-union establishment seemed to wear out. To our surprise, osteoblastogenesis seemed to be unaffected during early stages of non-union establishment. CONCLUSION: Taken together, we gained first insights into the establishment process of atrophic non unions, in which inflammatory processes accompanied by highly elevated osteoclast activity seem to play a leading role.

Extracorporeal membrane oxygenation for acute respiratory distress syndrome in burn patients: a case series and literature update.

BACKGROUND: Acute respiratory distress syndrome (ARDS) has a reported incidence of 34-43% in ventilated burn patients and is associated with a mortality of 59% in the severe form. The use and experience with extracorporeal membrane oxygenation (ECMO) in burn patients developing ARDS are still limited. We present our results and discuss the significance of ECMO in treating burn patients. METHODS: A retrospective analysis of burn patients treated with ECMO for ARDS between January 2017 and January 2019 was performed. Demographic, clinical, and outcome data were collected and analyzed. RESULTS: Eight burn patients were treated at our institution with ECMO in the designated time period. Of these, all but one patient had inhalation injury, burn percentage of TBSA was 37 ± 23%, ABSI score was 8.4 ± 2, and R-Baux-score was 98 ± 21. Seven patients developed severe ARDS and one patient moderate ARDS according to the Berlin classification with a PaO2/FiO2 ratio upon initiation of ECMO therapy of 62 ± 22 mmHg. ECMO duration was 388 ± 283 h. Three patients died from severe sepsis while five patients survived to hospital discharge. CONCLUSIONS: ECMO is a viable therapy option in burn patients developing severe ARDS and can contribute to survival rates similar to ECMO therapy in non-burn-associated severe ARDS. Consequently, patients with severe respiratory insufficiency with unsuccessful conventional treatment and suspected worsening should be transferred to burn units with the possibility of ECMO treatment to improve outcome.

Bone allografts combined with adipose-derived stem cells in an optimized cell/volume ratio showed enhanced osteogenesis and angiogenesis in a murine femur defect model.

Critical sized defects, especially in long bones, pose one of the biggest problems in orthopedic surgery. By definition, these defects do not heal without further treatment. Different therapeutic options range from autologous bone grafts, for example, free vascularized bone grafts, to commercially available bone allografts. Disadvantages of these bone allografts are related to reduced osteogenesis, since they are solely composed of cell-free bone matrix. The purpose of this study was to investigate the cell seeding efficiency of human adipose-derived stem cells (hASCs) on human bone allografts in vitro and furthermore analyze these optimized seeded allografts in a critical sized defect model in vivo. Cancellous human bone allografts were colonized with human ASCs in vitro. Cell seeding efficiency was evaluated by Cell Counting Kit-8 assay. Thereafter, optimized hASC-seeded bone scaffolds were examined in a murine femur defect model, stabilized with the MouseExFix system. Subsequently, x-ray analysis and histology were performed. Examination of cell seeding efficiency revealed an optimum starting population of 84,600 cells per 100 mm3 scaffold. In addition, scaffolds seeded with hASCs showed increased osteogenesis compared with controls. Histological analysis revealed increased remodeling and elevated new bone formation within hASC-seeded scaffolds. Moreover, immunohistochemical stainings revealed increased proliferation, osteogenesis, and angiogenesis. In this study, we systemically optimized cell/volume ratio of two promising components of tissue engineering: hASCs and human bone allografts. These findings may serve as a basis for future translational studies. KEY MESSAGES: Bone tissue engineering. Mesenchymal stem cells derived from human adipose tissue (hASCs). Optimal cell/volume ratio of cell-seeded scaffolds. Increased osteogenesis and angiogenesis in vivo.

Wnt Pathway in Bone Repair and Regeneration - What Do We Know So Far.

Wnt signaling plays a central regulatory role across a remarkably diverse range of functions during embryonic development, including those involved in the formation of bone and cartilage. Wnt signaling continues to play a critical role in adult osteogenic differentiation of mesenchymal stem cells. Disruptions in this highly-conserved and complex system leads to various pathological conditions, including impaired bone healing, autoimmune diseases and malignant degeneration. For reconstructive surgeons, critically sized skeletal defects represent a major challenge. These are frequently associated with significant morbidity in both the recipient and donor sites. The Wnt pathway is an attractive therapeutic target with the potential to directly modulate stem cells responsible for skeletal tissue regeneration and promote bone growth, suggesting that Wnt factors could be used to promote bone healing after trauma. This review summarizes our current understanding of the essential role of the Wnt pathway in bone regeneration and repair.

Age-dependent alterations in osteoblast and osteoclast activity in human cancellous bone.

It is assumed that the activity of osteoblasts and osteoclasts is decreased in bone tissue of aged individuals. However, detailed investigation of the molecular signature of human bone from young compared to aged individuals confirming this assumption is lacking. In this study, quantitative expression analysis of genes related to osteogenesis and osteoclastogenesis of human cancellous bone derived from the distal radius of young and aged individuals was performed. Furthermore, we additionally performed immunohistochemical stainings. The young group included 24 individuals with an average age of 23.2 years, which was compared to cancellous bone derived from 11 body donators with an average age of 81.0 years. In cancellous bone of young individuals, the osteogenesis-related genes RUNX-2, OSTERIX, OSTEOPONTIN and OSTEOCALCIN were significantly up-regulated compared to aged individuals. In addition, RANKL and NFATc1, both markers for osteoclastogenesis, were significantly induced in cancellous bone of young individuals, as well as the WNT gene family member WNT5a and the matrix metalloproteinases MMP-9. However, quantitative RT-PCR analysis of BMP-2, ALP, FGF-2, CYCLIN-D1, MMP-13, RANK, OSTEOPROTEGERIN and TGFb1 revealed no significant difference. Furthermore, Tartrate-resistant acid phosphatase (TRAP) staining was performed which indicated an increased osteoclast activity in cancellous bone of young individuals. In addition, pentachrome stainings revealed significantly less mineralized bone matrix, more osteoid and an increased bone density in young individuals. In summary, markers related to osteogenesis as well as osteoclastogenesis were significantly decreased in the aged individuals. Thus, the present data extends the knowledge about reduced bone regeneration and healing capacity observed in aged individuals.