Augmenting Breast Implant Research: Accessible Methods for Fabricating Miniature Smooth and Textured Breast Implants in a Laboratory Setting.

BACKGROUND: Because of the association of textured breast implants with breast implant-associated anaplastic large cell lymphoma, anatomically shaped breast implants, which rely on a textured surface to maintain rotational stability, have been recalled from the market. The dearth of anatomically shaped implants on the market reflects a need for novel breast implant technology, which has been traditionally developed by commercial breast implant manufacturers due to the complexities of implant manufacturing. To increase the accessibility of preclinical breast implant research, miniature breast implants made from polydimethylsiloxane were designed and fabricated for high throughput and low-cost prototyping and in vivo testing of both smooth and textured implants in a laboratory setting. METHODS: Two-piece negative molds measuring 2 × 1 cm were constructed in Fusion360 and 3D printed in Polysmooth filament. Textured molds were painted with a mixture of an epoxy and fine sugar or granular salt to create textured surfaces, while molds for smooth implants were smoothed using ethanol spray. Molds were injected with polydimethylsiloxane and cured for 12 hours at 37°C. The surface topography of laboratory-made implants and commercial textured and smooth implant shells was analyzed using scanning electron microscopy and implants were evaluated in vivo in an immunocompetent rodent model. RESULTS: Implants retained the original dome shape of the 3D-printed molds. Qualitative assessment of scanning electron microscopy images demonstrated similar surface topography between laboratory-made and commercial smooth and textured implants. There was no statistical difference in the diameter or density of the surface indentations of the Allergan's textured implant compared with laboratory-made textured implants ( P > 0.05). Finally, the surface topography and thickness of laboratory-made implant capsules were similar to previously published data using industry made miniature silicone devices implanted in rats. CONCLUSIONS: This study demonstrates a low-cost, highly customizable approach to fabricate miniature smooth and textured breast implant prototypes for in vivo studies. The accessibility of this implant fabrication strategy allows nonindustry investigators to develop novel implant designs more rapidly for preclinical investigation.

Charting the Effect of the Universal Offer Date on Plastic Surgery Residency Matches.

In 2019, the plastic surgery residency match changed their method for inviting students to interview. Instead of offering interview invitations and scheduling interviews on a first come, first served basis, all plastic surgery residency programs sent out secured interview spots on the same day. This universal offer date was intended to remove student worry that surrounded not scheduling an interview fast enough, as well as cause students to more carefully select which interview invitations to accept, increasing the likelihood that residency programs could interview only those students most interested in matching at their institutions. The effect of universal offer date was studied through analysis of available National Residency Match Program data, with a focus on the mean number of contiguous programs students ranked to match, as well as the mean number of applicants who residency programs ranked to fill each available position. Historical trends in plastic surgery match, trends in the match in other competitive surgical subspecialties, and applicant qualifications were also analyzed. In breaking with the general trend among all surgical subspecialties toward ranking more applicants per residency position, in 2020, fewer plastic surgery applicants were ranked by residency programs per available position, suggesting a more effective interview process and match. Matched applicant qualifications remained excellent across the period studied.

Prepectoral Breast Reconstruction Without the Use of Acellular Dermal Matrix: A 3-Year Review.

INTRODUCTION: Acellular dermal matrix (ADM) is frequently used during prepectoral tissue expander-based breast reconstruction. However, there has been a paucity of literature describing the experience of prepectoral reconstruction without the accompanying use of ADM. We seek to highlight our institutional experience with immediate prepectoral tissue expander placement without the use of ADM in breast reconstruction. METHODS: A retrospective, single-institution review of patient records was performed to identify all patients who underwent either skin sparing or nipple-sparing mastectomy with immediate tissue expander placement without the use of ADM. Demographics including age, body mass index, comorbidities, history of smoking or steroid use, perioperative radiation or chemotherapy, intraoperative details, and complication profiles during the tissue expander stage were retrospectively collected and analyzed. At the time of tissue expander placement, all mastectomy flaps were evaluated clinically and with indocyanine green laser angiography. Postoperative outcomes were tracked. RESULTS: Between 2017 and 2020, 63 patients (for a total of 108 breasts) underwent either skin sparing (16%) or nipple-sparing mastectomy (84%) with immediate prepectoral tissue expander without ADM placement. Fourteen percent of breasts developed postoperative cellulitis, 19% of breasts developed skin compromise, and 5% required a postoperative revisional procedure that did not result in immediate expander explant. There was a 13% (n = 14 breasts) explant rate occurring at a mean time of 74 days. Of those breasts that developed skin compromise, 45% went on to require eventual explant. Patients in the study were followed for an average of 6.3 months. CONCLUSIONS: Immediate prepectoral breast reconstruction using tissue expanders without ADM offers a viable alternative to established reconstructive paradigms. The major complication rate for prepectoral reconstruction without the use of ADM (17%) was found to be comparable with our historical subpectoral tissue expander reconstruction with ADM use. Tissue expander explant rates were also comparable between the prepectoral without ADM (13%) and the subpectoral with ADM cohorts. These preliminary data suggest that immediate breast reconstruction with tissue expander placement without accompanying ADM is viable alternative in the breast reconstructive algorithm.

Prepectoral Dual-Port Tissue Expander Placement: Can This Eliminate Suction Drain Use?

OBJECTIVES: The most common method of performing breast reconstruction after a mastectomy is using tissue expanders. Significant drainage that can lead to seromas and possible infection is a common sequela after mastectomies, and therefore, closed suction drains are routinely placed during the initial surgery (Vardanian et al. Plast Reconstr Surg. 2011;128:403-410). Drains, however, are associated with increased pain and discomfort for the patient and have been attributed to an increased infection rate by some authors (Degnim et al. Ann Surg. 2013;258:240-247; Saratzis et al. Clin Breast Cancer. 2009;9:243-246). We report on our experience using a dual-chamber tissue expander placed in the prepectoral space without acellular dermal matrix or other supportive material, which allows for drainage of periprosthetic fluid and avoids drain placement. PATIENTS AND METHODS: A retrospective, single-institution review of patients' records was performed for all patients who underwent prepectoral tissue expander placement between January 2018 and June 2019. Patients who had drains placed or who underwent autologous reconstruction in combination with expander placement were excluded. Thirty-nine patients were selected, with a total of 66 expander placements. Demographics including body mass index, comorbidities, history of smoking or steroid use, perioperative chemotherapy and radiation therapy, and intraoperative details and indications for surgery were retrospectively collected. Outcomes were separated into minor and major complications. Major complications were defined as complications that required surgical intervention. RESULTS: There were 51 prepectoral reconstructions with a dual-chamber tissue expander and no further surgical drain and 15 reconstructions using a standard expander with an additional closed suction drain. Overall complications for the no-drain cohort were 13.7% compared with 20% in the drain cohort (P = 0.68). Surgical site infection rate is 7.84% in the no-drain cohort compared with 13.3% in the drain cohort (P = 0.61). Mean numeric postoperative pain score at 6 hours was 3.2 in the no-drain cohort compared with 4.3 in the drain cohort (P = 0.03) and 4.17 compared with 5.6 at 12 hours, respectively (P = 0.04). Mean time to exchange of implant in the no-drain cohort was 152 days versus 126 days in the drain cohort (P = 0.38). Median follow-up times were 157 days for the no-drain cohort and 347 days for the drain cohort. CONCLUSIONS: Immediate breast reconstruction using a dual-chamber tissue expander offers a drain-free alternative to the immediate implant-based breast reconstruction. Our infection rate with 7.8% is lower than our own reported rates with subpectoral tissue expander reconstruction using either acellular dermal matrix or poly-4-hydroxybutyrate (17% and 11%). The overall complication rate is similar to historic data associated with breast reconstruction after mastectomy and suggests that dual-chamber expander placement offers a safe alternative possibly decreasing the patient's postoperative pain and discomfort that often is associated with closed suction drains (Saratzis et al. Clin Breast Cancer. 2009;9:243-246).

Modified V-Y Fasciocutaneous Flap Reconstruction After Abdominoperineal Resection in Irradiated Patients Prevents Wound Dehiscence and Associated Complications: A Retrospective Analysis and Benchtop Confirmation.

BACKGROUND: Primary perineal closure following abdominal perineal resection (APR) is reported to have a wound complication rate as high as 66%, whereas flap reconstruction reduces wound complications to 15% to 35%. A modified de-epithelialized V-Y fasciocutaneous flap aims to further improve results in this patient population. METHODS: To study the breaking force of a simple interrupted suture in either skin or subcutaneous fat, various quantitative assessments were performed in a porcine flap model using uniaxial static tensile testing with an Instron tensiometer, with a single or triple row of 3 Vicryl sutures in both skin and fat.An outcomes analysis was performed in 24 patients who underwent modified V-Y flap reconstruction after APR. Primary outcome was wound complications including infection, dehiscence, seroma, hematoma, and pelvic fluid collections. RESULTS: Tensile strength of sutures anchored in skin was found to be up to 8 times stronger than sutures anchored in subcutaneous fat in a single row and 3 times as strong in 3 rows (breaking force, 500.2 N vs 263.7 N). In our patient cohort of 24 irradiated cancer patients, 10 (42%) had wound healing complications. Wound dehiscence of various degrees accounted for 80% of these complications. Five patients with wound complications (50%) had associated pelvic fluid collections (infection, 1; wound dehiscence, 4). Minor dehiscence was more likely to occur after suture removal and less likely to be associated with pelvic collections compared to patients with major dehiscence. Our study yields total complication rates lower than what is reported in the literature for anterolateral thigh or gracilis flap including much lower infection rates, and almost similar results to the commonly used vertical rectus myocutaneous muscle. CONCLUSION: Tension-free de-epithelialized V-Y flap use after APR effectively reconstructs the defect while eliminating an additional donor site. Benchtop studies suggest enhanced flap integrity yielded by layered closure. Wound complications can be managed with local care in their majority (90%). Staggering or delaying suture removal can decrease minor dehiscence. Based on analysis of our results, review of the literature and consideration of donor site morbidity, we believe that modified V-Y flap is the best approach for APR reconstruction in irradiated patients.

Distinct effects of concomitant Jak2V617F expression and Tet2 loss in mice promote disease progression in myeloproliferative neoplasms.

Signaling mutations (eg, JAK2V617F) and mutations in genes involved in epigenetic regulation (eg, TET2) are the most common cooccurring classes of mutations in myeloproliferative neoplasms (MPNs). Clinical correlative studies have demonstrated that TET2 mutations are enriched in more advanced phases of MPNs such as myelofibrosis and leukemic transformation, suggesting that they may cooperate with JAK2V617F to promote disease progression. To dissect the effects of concomitant Jak2V617F expression and Tet2 loss within distinct hematopoietic compartments in vivo, we generated Jak2V617F/Tet2 compound mutant genetic mice. We found that the combination of Jak2V617F expression and Tet2 loss resulted in a more florid MPN phenotype than that seen with either allele alone. Concordant with this, we found that Tet2 deletion conferred a strong functional competitive advantage to Jak2V617F-mutant hematopoietic stem cells (HSCs). Transcriptional profiling revealed that both Jak2V617F expression and Tet2 loss were associated with distinct and nonoverlapping gene expression signatures within the HSC compartment. In aggregate, our findings indicate that Tet2 loss drives clonal dominance in HSCs, and Jak2V617F expression causes expansion of downstream precursor cell populations, resulting in disease progression through combinatorial effects. This work provides insight into the functional consequences of JAK2V617F-TET2 comutation in MPNs, particularly as it pertains to HSCs.

Polycationic Nanofibers for Nucleic Acid Scavenging.

Dying cells release nucleic acids (NA) and NA-containing complexes that activate inflammatory pathways of immune cells. Sustained activation of these pathways contributes to chronic inflammation frequently encountered in autoimmune and inflammatory diseases. In this study, grafting of cationic polymers onto a nanofibrous mesh enabled local scavenging of negatively charged pro-inflammatory molecules in the extracellular space. Nucleic acid scavenging nanofibers (NASFs) formed from poly(styrene-alt-maleic anhydride) conjugated with 1.8 kDa bPEI resulted in nanofibers of diameters 486 ± 9 nm. NASFs inhibited the NF-κB response stimulated by the negatively charged agonists, CpG and poly(I:C), in Ramos-blue cells but not Pam3CSK4, a nonanionic agonist. Moreover, NASFs significantly impeded NF-κB activation in cells stimulated with damage-associated molecular pattern molecules (DAMPs) released from doxorubicin killed cancer cells. In vivo application of NASFs to open wounds demonstrated nucleic acid scavenging in wounds of diabetic mice infected with Pseudomonas aeruginosa, suggesting the in vivo efficacy of NASFs. This simple technique of generating NASF results in effective localized anti-inflammation in vitro and local nucleic acid scavenging in vivo.

Depletion of Jak2V617F myeloproliferative neoplasm-propagating stem cells by interferon-α in a murine model of polycythemia vera.

Interferon-α (IFNα) is an effective treatment of patients with myeloproliferative neoplasms (MPNs). In addition to inducing hematological responses in most MPN patients, IFNα reduces the JAK2V617F allelic burden and can render the JAK2V617F mutant clone undetectable in some patients. The precise mechanism underlying these responses is incompletely understood and whether the molecular responses that are seen occur due to the effects of IFNα on JAK2V617F mutant stem cells is debated. Using a murine model of Jak2V617F MPN, we investigated the effects of IFNα on Jak2V617F MPN-propagating stem cells in vivo. We report that IFNα treatment induces hematological responses in the model and causes depletion of Jak2V617F MPN-propagating cells over time, impairing disease transplantation. We demonstrate that IFNα treatment induces cell cycle activation of Jak2V617F mutant long-term hematopoietic stem cells and promotes a predetermined erythroid-lineage differentiation program. These findings provide insights into the differential effects of IFNα on Jak2V617F mutant and normal hematopoiesis and suggest that IFNα achieves molecular remissions in MPN patients through its effects on MPN stem cells. Furthermore, these results support combinatorial therapeutic approaches in MPN by concurrently depleting dormant JAK2V617F MPN-propagating stem cells with IFNα and targeting the proliferating downstream progeny with JAK2 inhibitors or cytotoxic chemotherapy.

Distinct roles for long-term hematopoietic stem cells and erythroid precursor cells in a murine model of Jak2V617F-mediated polycythemia vera.

In the current model of the pathogenesis of polycythemia vera (PV), the JAK2V617F mutation arises in hematopoietic stem cells (HSCs) that maintain the disease, while erythroid precursor populations expand, resulting in excessive red blood cell production. We examined the role of these specific cell populations using a conditional Jak2V617F knockin murine model. We demonstrate that the most immature long-term (LT) HSCs are solely responsible for initiating and maintaining the disease in vivo and that Jak2V617F mutant LT-HSCs dominate hematopoiesis over time. When we induced Jak2V617F expression in erythropoietin receptor expressing precursor cells, the mice developed elevated hematocrit, expanded erythroid precursors, and suppressed erythropoietin levels. However, the disease phenotype was significantly attenuated compared with mice expressing Jak2V617F in LT-HSCs. In addition to developing a PV phenotype, all mice transplanted with Jak2V617F LT-HSCs underwent myelofibrotic transformation over time. These findings recapitulate the development of post-PV myelofibrosis in human myeloproliferative neoplasms. In aggregate, these results demonstrate the distinct roles of LT-HSCs and erythroid precursors in the pathogenesis of PV.

Osseous Maxillary Reconstruction with Immediate Dental Implant Placement: An Optimized Workflow for the Oncologic Patient.

INTRODUCTION: Maxillary reconstruction is a complex undertaking characterized by a 3-dimensional surgical site with deficiencies in multiple tissue types. Prior to virtual surgical planning(VSP), bony reconstruction was inaccurate and inefficient, thus reconstructions defaulted to soft tissue flaps or obturators. The current study describes an efficient and accurate approach to bony maxillary reconstruction with immediate dental implant placement(IDIP). METHODS: A reconstructive workflow was developed for osseous reconstruction to improve functional and aesthetic outcomes. Critical aspects include VSP, 3-D printed plates and IDIP. Review of a prospectively maintained database identified patients who underwent osseous maxillary reconstruction with a fibula flap and immediate dental implants from 2017-2022, with a focus on oncologic characteristics and reconstructive outcomes. RESULTS: During the study, 20 patients underwent maxillary reconstruction with VSP and IDIP. One dental implant out of 55 failed to osseointegrate and no flaps were lost. Three patients suffered partial loss of the fibula skin island; one required palatal closure with a radial forearm flap, and two were managed with outpatient debridement. Fifteen patients achieved either an interim or final retained dental prosthesis. All prostheses achieved acceptable aesthetic results without the instability associated with non-bone borne devices(e.g.dentures/obturators). No patients experienced delays in oncologic treatment. CONCLUSIONS: VSP technology has enabled surgeons to replace like with like to achieve better outcomes with acceptable morbidity for maxillary defects. IDIP provides all patients an opportunity for a fixed prosthesis even though not all complete the process. This maxillary reconstruction workflow can be safely accomplished in oncologic patients with promising and effective early results.

Coordinate loss of a microRNA and protein-coding gene cooperate in the pathogenesis of 5q- syndrome.

Large chromosomal deletions are among the most common molecular abnormalities in cancer, yet the identification of relevant genes has proven difficult. The 5q- syndrome, a subtype of myelodysplastic syndrome (MDS), is a chromosomal deletion syndrome characterized by anemia and thrombocytosis. Although we have previously shown that hemizygous loss of RPS14 recapitulates the failed erythroid differentiation seen in 5q- syndrome, it does not affect thrombocytosis. Here we show that a microRNA located in the common deletion region of 5q- syndrome, miR-145, affects megakaryocyte and erythroid differentiation. We find that miR-145 functions through repression of Fli-1, a megakaryocyte and erythroid regulatory transcription factor. Patients with del(5q) MDS have decreased expression of miR-145 and increased expression of Fli-1. Overexpression of miR-145 or inhibition of Fli-1 decreases the production of megakaryocytic cells relative to erythroid cells, whereas inhibition of miR-145 or overexpression of Fli-1 has a reciprocal effect. Moreover, combined loss of miR-145 and RPS14 cooperates to alter erythroid-megakaryocytic differentiation in a manner similar to the 5q- syndrome. Taken together, these findings demonstrate that coordinate deletion of a miRNA and a protein-coding gene contributes to the phenotype of a human malignancy, the 5q- syndrome.

Modifying hernia mesh design to improve device mechanical performance and promote tension-free repair.

PURPOSE: Approximately 348,000 ventral hernia repairs are performed annually in the United States and the incisional hernia recurrence rate is approximately 20% as a result of suture and mesh device failure. Device failure is related to changes at the suture/tissue interface that leads to acute or chronic suture pull-through and surgical failure. To better manage mechanical tension, we propose a modified mesh design with extensions and demonstrate its mechanical superiority. METHODS: Comparative uniaxial static tensile testing was conducted on polypropylene suture and a modified mesh. Subsequently, a standard of care (SOC) mesh and modified mesh were evaluated using a tensometer in an acute hernia bench-top model. RESULTS: Modified mesh breaking strength, extension knot breaking strength, extension disruption, and extension anchoring were superior to suture (p < .05). Modified mesh ultimate tensile strength of anchoring was superior to SOC mesh (p < .05). Various stitch patterns and modifications in device design significantly improved device tension-free performance far beyond clinically relevant benchmarks (p < .05). CONCLUSIONS: Testing demonstrates that the modified mesh outperforms SOC mesh and suture in all tested failure modes. SOC hernia mesh tears through tissue at stress levels below maximum physiologic stress, whereas, the modified hernia mesh is up to 200% stronger than SOC mesh at resisting suture tearing through tissue and maintains anchoring at stresses far beyond clinically relevant benchmarks. Modifying hernia mesh design significantly improves device mechanical performance and enhances tension-free repair.

Forearm-Based Turnover Muscle Flaps for Elbow Soft-Tissue Reconstruction: A Comparison of Regional Coverage Based on Distal Flap Perfusion.

BACKGROUND: Elbow wounds pose a reconstructive challenge. Prior studies have described the vascular anatomy of both the brachioradialis and flexor carpi ulnaris muscle flaps. The goal of this study was to describe the distal flap perfusion of the flexor carpi radialis, with a direct comparison of the brachioradialis, flexor carpi ulnaris, and flexor carpi radialis muscle flaps for coverage around the elbow. METHODS: Six fresh-frozen upper extremity specimens were dissected for brachioradialis, flexor carpi radialis, and flexor carpi ulnaris flaps. Vascular data from prior studies were combined with our anatomical measurements to determine the area of perfused coverage around the elbow for the brachioradialis and flexor carpi ulnaris. The flexor carpi radialis flap distal vascular perfusion was examined separately with transverse sections at 1-cm intervals after India ink injections to determine distal flap perfusion and elbow coverage. Perfusion data were plotted on x and y axes over the posterior elbow. RESULTS: The brachioradialis muscle covered an average of 56 percent of the x axis and 7.4 percent of the y axis. The flexor carpi ulnaris muscle covered an average of 90 percent of the elbow along the x axis and 23.3 percent of elbow along the y axis. The flexor carpi radialis covered an average of 34 percent of the x axis and 4.8 percent of the y axis. CONCLUSION: The flexor carpi ulnaris muscle provides the most versatile and robust coverage over the posterior elbow, followed by the brachioradialis muscle, which consistently provides coverage over the lateral epicondyle.

Association Between Targeted HER-2 Therapy and Breast Reconstruction Outcomes: A Propensity Score-Matched Analysis.

BACKGROUND: Current treatment for HER-2+ breast cancer includes chemotherapy and targeted HER-2 therapy with trastuzumab and/or pertuzumab. Evidence is lacking on the safety of breast reconstructive operations in these patients. We hypothesized that targeted HER-2 therapy was not associated with post-mastectomy reconstructive outcomes. STUDY DESIGN: Women receiving chemotherapy and post-mastectomy reconstruction at Duke University Medical Center from 2006 to 2016 were retrospectively identified. Patients receiving targeted HER-2 therapy with trastuzumab and/or pertuzumab within 6 weeks before breast reconstruction were propensity score-matched 1:1 to patients who did not receive targeted HER-2 therapy, based on the following factors: age, obesity, diabetes, tobacco use, receipt of neoadjuvant chemotherapy, chemotherapy regimen, and radiation therapy. Primary study outcomes included the occurrence of hematoma, seroma, infection, wound breakdown, mastectomy skin flap necrosis, and postoperative flap thrombosis. RESULTS: A total of 481 women were identified, resulting in 107 propensity score-matched pairs. Administration of combined trastuzumab and pertuzumab therapy before breast reconstruction was independently associated with increased risk of postoperative wound breakdown requiring operative intervention for closure, compared with patients not undergoing targeted HER-2 therapy (odds ratio 65.29; 95% CI 1.63 to 2,611.50; p = 0.03). In addition, larger tumor size (2 to 5 cm) was significantly associated with a reduced risk of postoperative wound breakdown, compared with smaller tumors (<2 cm) (odds ratio 0.41; 95% CI 0.19 to 0.87; p = 0.02). Single-agent targeted HER-2 therapy with trastuzumab was not significantly associated with reconstructive complications. CONCLUSIONS: Our study suggests that trastuzumab therapy in conjunction with breast reconstructive operation is not associated with reconstructive complications, and breast reconstruction does not need to be delayed due to the administration of trastuzumab. Future studies are needed to evaluate the impact of pertuzumab on surgical outcomes.

In Vivo RNAi screening identifies a leukemia-specific dependence on integrin beta 3 signaling.

We used an in vivo small hairpin RNA (shRNA) screening approach to identify genes that are essential for MLL-AF9 acute myeloid leukemia (AML). We found that Integrin Beta 3 (Itgb3) is essential for murine leukemia cells in vivo and for human leukemia cells in xenotransplantation studies. In leukemia cells, Itgb3 knockdown impaired homing, downregulated LSC transcriptional programs, and induced differentiation via the intracellular kinase Syk. In contrast, loss of Itgb3 in normal hematopoietic stem and progenitor cells did not affect engraftment, reconstitution, or differentiation. Finally, using an Itgb3 knockout mouse model, we confirmed that Itgb3 is dispensable for normal hematopoiesis but is required for leukemogenesis. Our results establish the significance of the Itgb3 signaling pathway as a potential therapeutic target in AML.