Pyoderma gangrenosum following reduction mammoplasty: Systematic review of the literature and case report.

BACKGROUND: Pyoderma gangrenosum (PG) is a rare inflammatory neutrophilic dermatosis that can develop at a surgical site. Diagnosis can be challenging at its presentation causing delays in appropriate treatment. The aim of this study is to review the current literature as well as to describe the clinical presentation, diagnostic pathway, and treatment of PG after reduction mammaplasty in order to define a standardized multidisciplinary diagnostic and therapeutic approach. In the future, this may ease early identification and prompt treatment, and eventually minimize severe morbidity and long-term sequelae. METHODS: The entire PubMed/Medline database was screened following the PRISMA guidelines to identify studies describing PG that have occurred after reduction mammoplasty. RESULTS: Twenty-eight articles including 31 patients reported a PG after breast reduction surgery between January 1988 and March 2022. Twenty-one (68%) patients presented with skin ulcerations, 14 (45%) with erythema, and 5 (16%) with vesicles. Out of the 30 cases that underwent bilateral surgery, 18 (60%) developed PG bilaterally. In 12 out of 31 patients, nipple-areolar complex (NAC) involvement was evaluated, though in 10 patients (83%) the NAC was spared. Of the 20 patients (65%) who underwent skin biopsies for histopathological examination, 18 (90%) showed neutrophilic infiltration of the dermal layers. All 31 patients (100%) showed rapid clinical improvement after the introduction of immunosuppressive therapy. CONCLUSIONS: PG can result in devastating skin alterations also after reduction mammoplasty, if misdiagnosed. However, it presents with constant yet unspecific local and general signs and symptoms that can be recognized to early initiate an appropriate pharmacological treatment.

Aesthetic training concept during plastic surgery residency - Opportunity or risk?

Background: Aesthetic surgery training renders to be challenging to acquire sufficient hands-on experience during residency. To resolve this problem, the "Munich Model" was established in our clinic: Senior residents perform aesthetic surgeries, supervised by an experienced plastic surgeon while patients benefit from reduced surgery costs. With this model, we hypothesize no significant differences in the postoperative outcome between procedures performed by residents and plastic surgeons. Methods: Between August 2012 and December 2017, 481 aesthetic surgeries were included in this retrospective single-center study, of which 283 were performed by residents and 198 by plastic surgeons. Procedures included mastopexy, abdominoplasty, extremity lift, breast reduction, breast augmentation, facial surgery, aesthetic liposuction and lipedema liposuction. Postoperative outcomes were compared regarding surgery time, time of drain removal, inpatient length of stay, duration of wound healing, perioperative blood loss and occurrence of major (surgical revision needed) and minor complications (no surgery needed). Results: We found no significant differences in aesthetic surgical procedures between residents and board-certified plastic surgeons in the outcome measures of surgery duration, time of drain removal, inpatient length of stay, perioperative blood loss and complication rate, including major and minor complications. Only the inpatient stay was prolonged in aesthetic liposuctions performed by residents. Conclusion: This study demonstrates comparatively that supervised aesthetic surgeries at a university hospital utilizing the "Munich Model" widely meet the specialist surgeons' standards.

Microvascular Fragments Protect Ischemic Musculocutaneous Flap Tissue from Necrosis by Improving Nutritive Tissue Perfusion and Suppressing Apoptosis.

Microvascular fragments (MVF) derived from enzymatically digested adipose tissue are functional vessel segments that have been shown to increase the survival rate of surgical flaps. However, the underlying mechanisms have not been clarified so far. To achieve this, we raised random-pattern musculocutaneous flaps on the back of wild-type mice and mounted them into dorsal skinfold chambers. The flaps were injected with MVF that were freshly isolated from green fluorescent protein-positive (GFP+) donor mice or saline solution (control). On days 1, 3, 5, 7, and 10 after surgery, intravital fluorescence microscopy was performed for the quantitative assessment of angiogenesis, nutritive blood perfusion, and flap necrosis. Subsequently, the flaps were analyzed by histology and immunohistochemistry. The injection of MVF reduced necrosis of the ischemic flap tissue by ~20%. When compared to controls, MVF-injected flaps also displayed a significantly higher functional capillary density and number of newly formed microvessels in the transition zone, where vital tissue bordered on necrotic tissue. Immunohistochemical analyses revealed a markedly lower number of cleaved caspase-3+ apoptotic cells in the transition zone of MVF-injected flaps and a significantly increased number of CD31+ microvessels in both the flaps' base and transition zone. Up to ~10% of these microvessels were GFP+, proving their origin from injected MVF. These findings demonstrate that MVF reduce flap necrosis by increasing angiogenesis, improving nutritive tissue perfusion, and suppressing apoptosis. Hence, the injection of MVF may represent a promising strategy to reduce ischemia-induced flap necrosis in future clinical practice.

Relevance of the Scaphoid Shift Test for the Investigation of Scapholunate Ligament Injuries.

Background: Although it is part of the common clinical examination of scapholunate ligament pathologies, there are only little data on the diagnostic value of the scaphoid shift test. The aim of this study was to evaluate the scaphoid shift test in a large cohort of patients. Materials and Methods: We retrospectively analysed 447 patients who underwent the scaphoid shift test and wrist arthroscopy because of various suspected injuries of the wrist, correlating the results of clinical examination with data obtained during the wrist arthroscopy. Sensitivity, specificity, and positive and negative predictive values were calculated and evaluated. Results: The sensitivity of the scaphoid shift test was low (0.50) when examining the whole cohort. In a subgroup of patients specifically referred for suspected scapholunate ligament injury, the sensitivity was higher (0.61), but the specificity was low (0.62). In detecting more serious lesions (Geissler 3 + 4), the scaphoid shift test demonstrated higher sensitivity (0.66). Conclusions: An isolated scaphoid shift test may only be of limited value in the diagnosis of scapholunate ligament lesions and should, therefore, be viewed as a useful tool for a preliminary assessment, but a negative test should not prevent the surgeon from indicating a more extensive diagnostic workup.

[The Value of Synthetic and Biologic Meshes in Implant-Based Breast Reconstruction]. / Der Stellenwert von synthetischen Netzen und biologischen Matrices in der Implantat-basierten Brustrekonstruktion.

Implant based breast reconstruction (IBBR) keeps evolving and has been influenced heavily by the use of synthetic and biologic meshes in the last years. In both, subpectoral as well as prepectoral approaches the use of synthetic and biologic meshes has made it possible to place implants precisely according to the breast's footprint and strengthen soft-tissue coverage, particularly in the lower pole of the breast with lower complication rates and better cosmesis. Various mesh options that differ in material, processing, size and cost are currently in clinical use. This review aims to define the role of biologic and synthetic meshes in IBBR regarding the advantages and disadvantages of their use.

[The Significance of Oncoplastic Breast Reconstruction After Tumorectomy in Surgical Breast Cancer Therapy]. / Der Stellenwert der onkoplastischen Brustrekonstruktion nach Tumorektomie in der chirurgischen Brustkrebs-Behandlung.

Breast-conserving therapy (BCT), meaning tumorectomy in combination with systemic therapy and locoregional radiation therapy has become the preferred method to treat early-stage breast cancer. With excellent long-term recurrence-free and overall survival rates, breast surgeons today must deliver du- rable and aesthetically appealing results that guarantee a good quality of life to meet the high patient expectations. Oncoplas- tic breast surgery (OPBS) is an innovative approach to improve the overall results of BCT. Often carried out by a team of a plastic surgeon and an oncologic breast surgeon, OPBS can actively prevent breast deformities without compromising oncological safety. In the following, an overview of the principles and techniques of oncoplastic breast surgery will be given due to its ever-increasing significance and its advantages and dis- advantages will be discussed in the context of reconstructive breast surgery.

Bromelain Protects Critically Perfused Musculocutaneous Flap Tissue from Necrosis.

Bromelain has previously been shown to prevent ischemia-induced necrosis in different types of tissues. In the present study, we, therefore, evaluated for the first time, the tissue-protective effects of bromelain in musculocutaneous flaps in mice. Adult C57BL/6N mice were randomly assigned to a bromelain treatment group and a control group. The animals were treated daily with intraperitoneal injections of 20 mg/kg bromelain or saline (control), starting 1 h before the flap elevation throughout a 10-day observation period. The random-pattern musculocutaneous flaps were raised on the backs of the animals and mounted into a dorsal skinfold chamber. Angiogenesis, nutritive blood perfusion and flap necrosis were quantitatively analyzed by means of repeated intravital fluorescence microscopy over 10 days after surgery. After the last microscopy, the flaps were harvested for additional histological and immunohistochemical analyses. Bromelain reduced necrosis of the critically perfused flap tissue by ~25%. The bromelain-treated flaps also exhibited a significantly higher functional microvessel density and an elevated formation of newly developed microvessels in the transition zone between the vital and necrotic tissues when compared to the controls. Immunohistochemical analyses demonstrated a markedly lower invasion of the myeloperoxidase-positive neutrophilic granulocytes and a significantly reduced number of cleaved caspase 3-positive apoptotic cells in the transition zone of bromelain-treated musculocutaneous flaps. These findings indicate that bromelain prevents flap necrosis by maintaining nutritive tissue perfusion and by suppressing ischemia-induced inflammation and apoptosis. Hence, bromelain may represent a promising compound to prevent ischemia-induced flap necrosis in clinical practice.

Implant-Based Breast Reconstruction after Mastectomy, from the Subpectoral to the Prepectoral Approach: An Evidence-Based Change of Mind?

Over the last years, prepectoral implant-based breast reconstruction has undergone a renaissance due to several technical advancements regarding mastectomy techniques and surgical approaches for the placement and soft tissue coverage of silicone implants. Initially abandoned due to the high incidence of complications, such as capsular contraction, implant extrusion, and poor aesthetic outcome, the effective prevention of these types of complications led to the prepectoral technique coming back in style for the ease of implant placement and the conservation of the pectoralis muscle function. Additional advantages such as a decrease of postoperative pain, animation deformity, and operative time contribute to the steady gain in popularity. This review aims to summarize the factors influencing the trend towards prepectoral implant-based breast reconstruction and to discuss the challenges and prospects related to this operative approach.

A Modified Burn Comb Model With a New Dorsal Frame That Allows for Local Treatment in Partial-Thickness Burns in Rats.

Burn wound progression (BWP) leads to vertical and horizontal injury extension. The "burn comb model" is commonly used, in which a full-thickness burn with intercalated unburned interspaces is induced. We aimed to establish an injury progressing to the intermediate dermis, allowing repeated wound evaluation. Furthermore, we present a new dorsal frame that enables topical drug application. Eight burn fields and six interspaces were induced on each of 17 rats' dorsa with a 10-second burn comb application. A developed 8-panel aluminum frame was sutured onto 12 animals and combined with an Elizabethan collar. Over 14 days, macroscopic and histologic wound assessment and laser speckle contrast imaging (LSCI) were performed besides evaluation of frame durability. The 10-second group was compared with nine animals injured with a full-thickness 60-second model. Frame durability was sufficient up to day 4 with 8 of the 12 frames (67%) still mounted. The 60-second burn led to an increased extent of interspace necrosis (P = .002). The extent of necrosis increased between days 1 and 2 (P = .001), following the 10-second burn (24% ± SEM 8% to 40% ± SEM 6%) and the 60-second burn (57% ± SEM 6% to 76% ± SEM 4%). Interspace LSCI perfusion was higher than burn field perfusion. It earlier reached baseline levels in the 10-second group (on day 1: 142% ± SEM 9% vs 60% ± SEM 5%; P < .001). Within day 1, the 10-second burn showed histological progression to the intermediate dermis, both in interspaces and burn fields. This burn comb model with its newly developed fixed dorsal frame allows investigation of topical agents to treat BWP in partial-thickness burns.

Boosting Tissue Vascularization: Nanofat as a Potential Source of Functional Microvessel Segments.

Nanofat is increasingly applied in plastic surgery for the improvement of scar quality and skin rejuvenation. However, little is known about the underlying regenerative mechanisms. Therefore, we herein investigated nanofat grafts in a murine dorsal skinfold chamber model. Nanofat generated from subcutaneous, inguinal adipose tissue of green fluorescent protein (GFP)+ C57BL/6 male and female donor mice was injected intracutaneously into dorsal skinfold chambers of gender-matched GFP- wild-type mice. The vascularization and tissue composition of the grafted nanofat were analyzed by means of intravital fluorescence microscopy, histology and immunohistochemistry over an observation period of 14 days. The freshly generated nanofat consisted of small fragments of perilipin+ adipocytes surrounded by Sirius red+ collagen fibers and still contained intact CD31+/GFP+ vessel segments. After transplantation into the dorsal skinfold chamber, these vessel segments survived and developed interconnections to the surrounding CD31+/GFP- host microvasculature. Accordingly, the grafted nanofat rapidly vascularized and formed new microvascular networks with a high functional microvessel density on day 14 without marked differences between male and female mice. Even though further research is needed to confirm these findings, the present study suggests that nanofat boosts tissue vascularization. Thus, nanofat may represent a versatile resource for many applications in tissue engineering and regenerative medicine.

Corrigendum to "Do your surgical glove characteristics and wearing habits affect your tactile sensibility?" [Ann. Med. Surg. Volume 57, September 2020, Pages 281-286].

[This corrects the article DOI: 10.1016/j.amsu.2020.08.002.].

Bacterial bioburden of wounds: influence of debridement and negative-pressure wound therapy (NPWT).

OBJECTIVE: To clarify the role of microbiological swabs in surgical decision-making, we investigated the effect of negative-pressure wound therapy (NPWT) and serial surgical debridement on bacterial bioburden in hard-to-heal wounds and ultimately correlated them with the success of surgical closure. METHOD: All patients were treated with surgical debridement, jet lavage and NPWT before their wounds were finally closed. The treatment effect was assessed by correlating microbiological swabs obtained immediately after intervention with those obtained after removal of the dressings during the following surgical procedures. The result of the last microbiological swab taken before definitive surgical closure was correlated with the requirement for revision surgery. RESULTS: We included the results of 704 microbiological swabs from 97 patients in 110 wound localisations in this monocentric, retrospective study. NPWT did not improve bacterial bioburden in 77% of cases and the duration of NPWT did not affect the result. Furthermore, no significant effect of NPWT could be found for either anaerobic (p=0.96) or aerobic bacteria (p=0.43). In contrast, surgical debridement decreased bacterial load in approximately 60% of cases. If sterile wound swabs could be obtained at all, it was during the first four surgical debridements in 60% of patients; after that only 10% became sterile. CONCLUSIONS: Sterile microbiological wound swabs before surgical closure were associated with lower rates of revision surgery, while low or medium bacterial loads did not increase revision rates.

Improved Vascularization and Survival of White Compared to Brown Adipose Tissue Grafts in the Dorsal Skinfold Chamber.

Fat grafting is a frequently applied procedure in plastic surgery for volume reconstruction. Moreover, the transplantation of white adipose tissue (WAT) and brown adipose tissue (BAT) increasingly gains interest in preclinical research for the treatment of obesity-related metabolic defects. Therefore, we herein directly compared the vascularization capacity and survival of WAT and BAT grafts. For this purpose, size-matched grafts isolated from the inguinal WAT pad and the interscapular BAT depot of C57BL/6N donor mice were syngeneically transplanted into the dorsal skinfold chamber of recipient animals. The vascularization and survival of the grafts were analyzed by means of intravital fluorescence microscopy, histology, and immunohistochemistry over an observation period of 14 days. WAT grafts showed an identical microvascular architecture and functional microvessel density as native WAT. In contrast, BAT grafts developed an erratic microvasculature with a significantly lower functional microvessel density when compared to native BAT. Accordingly, they also contained a markedly lower number of CD31-positive microvessels, which was associated with a massive loss of perilipin-positive adipocytes. These findings indicate that in contrast to WAT grafts, BAT grafts exhibit an impaired vascularization capacity and survival, which may be due to their higher metabolic demand. Hence, future studies should focus on the establishment of strategies to improve the engraftment of transplanted BAT.

Do your surgical glove characteristics and wearing habits affect your tactile sensibility?

BACKROUND: Tactile sensibility plays a critical role in medicine, especially in surgical practice. In order to prevent surgical site infections and protect the surgeon, the use of surgical gloves is standard practice. However, wearing these might affect the sensibility of the hand disadvantageously, especially in disciplines that require precision work. METHODS: We evaluated the influence of six different glove types, as well as gloves wearing habits (double gloving, over- and undersized gloves) on tactile sensibility using two-point-discrimination and Semmes-Weinstein monofilament testing in 27 non-surgeons. RESULTS: There were significant differences regarding tactile sensibility of gloved compared to bare hands and between different types of gloves. While undersized gloves and double gloving did not affect tactile sensibility, oversized gloves were associated with a significant deterioration of the sensibility of the hand in the Semmes-Weinstein monofilament test. CONCLUSION: This study demonstrates that surgical gloves negatively affect the sensibility of the hand and show significant differences between different types of gloves.

New Insights on Lipedema: The Enigmatic Disease of the Peripheral Fat.

BACKGROUND: Although a large number of adult women worldwide are affected by lipedema, the physiologic conditions triggering onset and progression of this chronic disease remain enigmatic. In the present study, a descriptive epidemiologic situation of postoperative lipedema patients is presented. METHODS: The authors developed an online survey questionnaire for lipedema patients in Germany. The survey was conducted on 209 female patients who had been diagnosed with lipedema and had undergone tumescent liposuction. RESULTS: Most of the participants (average age, 38.5 years) had noticed a first manifestation of the disease at the age of 16. It took a mean of 15 years to accomplish diagnosis. Liposuction led to a significant reduction of pain, swelling, tenderness, and easy bruising as confirmed by the majority of patients. Hypothyroidism [n = 75 (35.9 percent) and depression [n = 48 (23.0 percent)] occurred at a frequency far beyond the average prevalence in the German population. The prevalence of diabetes type 1 [n = 3 (1.4 percent)], and diabetes type 2 [n = 2 (1 percent)] was particularly low among the respondents. Forty-seven of the lipedema patients (approximately 22.5 percent) suffered from a diagnosed migraine. Following liposuction, the frequency and/or intensity of migraine attacks became markedly reduced, as stated by 32 patients (68.1 percent). CONCLUSIONS: Quality of life increases significantly after surgery with a reduction of pain and swelling and decreased tendency to easy bruising. The high prevalence of hypothyroidism in lipedema patients could be related to the frequently observed lipedema-associated obesity. The low prevalence of diabetes, dyslipidemia, and hypertension appears to be a specific characteristic distinguishing lipedema from lifestyle-induced obesity.

Adipose Stem Cells from Lipedema and Control Adipose Tissue Respond Differently to Adipogenic Stimulation In Vitro.

BACKGROUND: Lipedema is characterized by localized accumulation of fat in the extremities, which is typically unresponsive to dietary regimens or physical activity. Although the disease is well described and has a high incidence, little is known regarding the molecular and cellular mechanisms underlying its pathogenesis. The aim of this study was to investigate the pathophysiology of lipedema adipose cells in vitro. METHODS: Adipose-derived stem cells were isolated from lipoaspirates derived from lipedema and nonlipedema patients undergoing tumescent liposuction. In vitro differentiation studies were performed for up to 14 days using adipogenic or regular culture medium. Supernatants and cell lysates were tested for adiponectin, leptin, insulin-like growth factor-1, aromatase (CYP19A1), and interleukin-8 content at days 7 and 14, using enzyme-linked immunosorbent assays. Adipogenesis was evaluated by visualizing and measuring cytoplasmic lipid accumulation. RESULTS: Lipedema adipose-derived stem cells showed impeded adipogenesis already at early stages of in vitro differentiation. Concomitant with a strongly reduced cytoplasmic lipid accumulation, significantly lower amounts of adiponectin and leptin were detectable in supernatants from lipedema adipose-derived stem cells and adipocytes compared with control cells. In addition, lipedema and nonlipedema cells differed in their expression of insulin-like growth factor-1, aromatase (CYP19A1), and interleukin-8 and in their proliferative activity. CONCLUSIONS: The authors' findings indicate that in vitro adipogenesis of lipedema adipose-derived stem cells is severely hampered compared with nonlipedema adipose-derived stem cells. Lipedema adipose cells differ not only in their lipid storage capacity but also in their adipokine expression pattern. This might serve as a valuable marker for diagnosis of lipedema, probably from an early stage on.

In Vitro Characterization of Hypoxia Preconditioned Serum (HPS)-Fibrin Hydrogels: Basis for an Injectable Biomimetic Tissue Regeneration Therapy.

Blood-derived growth factor preparations have long been employed to improve perfusion and aid tissue repair. Among these, platelet-rich plasma (PRP)-based therapies have seen the widest application, albeit with mixed clinical results to date. Hypoxia-preconditioned blood products present an alternative to PRP, by comprising the complete wound healing factor-cascade, i.e., hypoxia-induced peripheral blood cell signaling, in addition to platelet-derived factors. This study set out to characterize the preparation of hypoxia preconditioned serum (HPS), and assess the utility of HPS-fibrin hydrogels as vehicles for controlled factor delivery. Our findings demonstrate the positive influence of hypoxic incubation on HPS angiogenic potential, and the individual variability of HPS angiogenic factor concentration. HPS-fibrin hydrogels can rapidly retain HPS factor proteins and gradually release them over time, while both functions appear to depend on the fibrin matrix mass. This offers a means of controlling factor retention/release, through adjustment of HPS fibrinogen concentration, thus allowing modulation of cellular angiogenic responses in a growth factor dose-dependent manner. This study provides the first evidence that HPS-fibrin hydrogels could constitute a new generation of autologous/bioactive injectable compositions that provide biochemical and biomaterial signals analogous to those mediating physiological wound healing. This therefore establishes a rational foundation for their application towards biomimetic tissue regeneration.

Long-term pre- and postconditioning with low doses of erythropoietin protects critically perfused musculocutaneous tissue from necrosis.

It has been shown that pre- and postconditioning of ischemically challenged tissue with erythropoietin (EPO) is able to reduce necrosis in a dose-dependent manner. The aim of this study was to determine the tissue-protective effects of different EPO dosages and administration regimes. Three groups of six C57Bl/6-mice each were analyzed: (1) pre- and postconditioning with initial high doses of EPO (starting at 2500 I.U./kg bw i.p.) followed by low doses of EPO (125 I.U./kg bw i.p.) (EPO-high-dose); (2) pre- and postconditioning with low doses of EPO (125 I.U./kg bw i.p.) (EPO-low-dose); and (3) untreated control group. Randomly perfused musculocutaneous flaps were mounted on dorsal skinfold chambers undergoing acute persistent ischemia and developing ∼50% necrosis without treatment. Intravital epifluorescence microscopy was performed at days 1, 3, 5, 7, and 10 after surgery, assessing flap necrosis, microcirculation, and angiogenesis. The hematocrit was measured at days 0, 3, 7, and 10. Only the EPO-low-dose regimen was associated with a significant reduction of necrosis when compared to untreated controls. EPO-low-dose showed a higher increase in both arteriolar diameter and velocity, thereby resulting in a significantly increased arteriolar blood flow and a hence higher functional capillary density (FCD) of the critically perfused zone. EPO-induced angiogenesis was significantly increased in EPO-low-dose at days 7 and 10. Only EPO-high-dose reached a significant hematocrit increase by day 10. Tissue pre- and postconditioning with low doses of EPO protects the critically perfused musculocutaneous tissue by maintaining capillary perfusion because of increased arteriolar blood flow mediated by nitric oxide (NO) expression.

Four-corner fusion: Comparing outcomes of conventional K-wire-, locking plate-, and retrograde headless compression screw fixations.

PURPOSE: Several operative approaches and various implants for osseous fixation have been described to achieve four-corner fusion of the wrist. Given the discordance and to aid in further standardizing the technique, this study directly compares the outcomes of K-wire, fusion plate, and headless retrograde compressive screw fixations to achieve four-corner arthrodesis. METHODS: Sixty-four patients underwent four-corner fusion over a period of 5 years and were reviewed retrospectively. Twenty-one patients underwent bone fixation with conventional K-wires, 26 with locking plates, and 17 patients were treated by headless retrograde compressive screw fixations. Patients of the different groups were comparable regarding age, sex, hand dominance, and stage of disease. RESULTS: All study groups showed significant improvements in grip strength, decrease in pain (NRS) at rest and with activity, range-of-motion of the wrist, and wrist function (measured by the DASH-score). When evaluating the three groups amongst each other, overall complication and nonunion rates were low and revealed no significant differences between the groups of patients. However, regarding postoperative NRS at activity, dorsal flexion, and DASH-scores, the "screw" group showed significantly better results than the "wire" group. CONCLUSION: The results show that all examined techniques of four-corner fusion can improve wrist function when compared to preoperative baseline (NRS at rest and activity, postoperative DASH-scores). However, headless retrograde compressive screw fixation had significant better results regarding pain relief (NRS) at activity and postoperative DASH-scores.

Development of photosynthetic sutures for the local delivery of oxygen and recombinant growth factors in wounds.

Surgical sutures represent the gold standard for wound closure, however, their main purpose is still limited to a mechanical function rather than playing a bioactive role. Since oxygen and pro-regenerative growth factors have been broadly described as key players for the healing process, in this study we evaluated the feasibility of generating photosynthetic sutures that, in addition to mechanical fixation, could locally and stably release oxygen and recombinant human growth factors (VEGF, PDGF-BB, or SDF-1α) at the wound site. Here, photosynthetic genetically modified microalgae were seeded in commercially available sutures and their distribution and proliferation capacity was evaluated. Additionally, the mechanical properties of seeded sutures were compared to unseeded controls that showed no significant differences. Oxygen production, as well as recombinant growth factor release was quantified in vitro over time, and confirmed that photosynthetic sutures are indeed a feasible approach for the local delivery of bioactive molecules. Finally, photosynthetic sutures were tested in order to evaluate their resistance to mechanical stress and freezing. Significant stability was observed in both conditions, and the feasibility of their use in the clinical practice was therefore confirmed. Our results suggest that photosynthetic gene therapy could be used to produce a new generation of bioactive sutures with improved healing capacities. STATEMENT OF SIGNIFICANCE: Disruption of the vascular network is intrinsic to trauma and surgery, and consequently, wound healing is characterized by diminished levels of blood perfusion. Among all the blood components, oxygen and pro-regenerative growth factors have been broadly described as key players for the healing process. Therefore, in this study we evaluated the feasibility of generating photosynthetic sutures that, in addition to mechanical fixation, could locally and stably release oxygen and recombinant human growth factors at the wound site. This novel concept has never been explored before for this type of material and represents the first attempt to create a new generation of bioactive sutures with improved regenerative capabilities.