Tissue Engineering Auricular Cartilage: A Review of Auricular Cartilage Characteristics and Current Techniques for Auricular Reconstruction.

Microtia and anotia are congenital auricular anomalies that negatively impact the psychosocial development of those affected. Because auricular cartilage is a type of elastic cartilage that lacks regenerative capacity, any notable defect in its structure requires a surgical approach to reconstructing the auricle. While there are several reconstructive options available between alloplastic and prosthetic implants, autologous rib cartilage grafts remain the most commonly used treatment modality. Still, this widely used technique is accompanied by significant patient discomfort in a young child and carries additional risks secondary to the traumatic process of rib cartilage extraction, such as pneumothorax and chest wall deformities, and the final esthetic results may not be ideal. To circumvent these limitations, tissue engineering approaches have been used to create a realistic-looking ear that mirrors the complex anatomy of the normal ear. This article reviews the biochemical and biomechanical properties of human auricular cartilage as they relate to design criteria. In addition, a variety of cell sources, biocompatible scaffolds, scaffold-free techniques, and mechanical and biological stimuli are discussed. This review aims to identify knowledge gaps in the literature related to auricular cartilage characteristics and make recommendations to drive the field of auricular tissue engineering.

Vitamin C, lactoferrin and elastin-Advancing the science.

BACKGROUND: This study follows an initial scientific validation linking sodium ascorbate (SAC) with elastin conservation and the clinical trial histology observation that the full formulation tested there stimulated elastin development. In an effort to explain the increased elastin response, a candidate was sought that may provide synergy to SAC during elastin stimulation. Lactoferrin was the constituent chosen to explore in this realm. MATERIALS AND METHODS: Using the previously described ex vivo skin model, freshly collected discarded human skin from 2 donors was used to evaluate the effects of lactoferrin and SAC alone and together, and L-ascorbate CE Ferulic formulation (CEF) on elastogenesis. Four skin explants were topically subjected to the treatments daily for 7 days and one group was left untreated as a negative control. The tissue was fixed and embedded. Sections were evaluated by immunofluorescence using antibodies targeting Tropoelastin and CD44, with DAPI counterstaining to observe nuclei. Images were then analyzed using ImageJ. RESULTS: Treatment with SAC and lactoferrin demonstrated a significant synergistic effect on tropoelastin stimulation compared to the single treatments. In addition, this combination demonstrated intact and increased elastin fibers in contrast to the CEF, which portrayed fragmented elastin fibers. In addition, an additive effect of SAC also contributed to the enhanced CD44, suggesting an increased presence of hyaluronic acid, a new observation for this compound. CONCLUSION: This study complements a series of studies that have been undertaken to validate the efficacy of a novel antioxidant formulation. Aside from its efficacy in ROS management, the SAC constituent is unique in the different forms of Vitamin C for its ability to conserve elastin. Prior clinical studies demonstrated additive elastin stimulation on histology, not just conservation. From this current study, the combination of SAC with lactoferrin may be responsible for this additive stimulatory effect on elastin. This presents a significant advance in topical antioxidant formulations where the Vitamin C component provides antioxidant and collagen stimulation with additional elastin stimulation rather than degradation.

Antioxidants with proven efficacy and elastin-conserving vitamin C-A new approach to free radical defense.

BACKGROUND: This paper describes the background research and validation related to the formulation of a novel antioxidant product. Two defined outcomes were sought. Firstly, a combined efficacy of antioxidant ingredients in quenching free oxygen radicals. Secondly, the investigation into whether a vitamin C derivative sodium salt was elastin conserving in contrast to current vitamin C/l-ascorbic acid variations that have been reported to negatively affect elastin constitution and regeneration. MATERIALS AND METHODS: A leading l-ascorbic acid antioxidant available on the market was compared with the experimental new product in two studies. In the first experiment, the products were compared to assess their antioxidant properties. The evaluated products TOPICAL ANTIOXIDANT 1 and TOPICAL ANTIOXIDANT 2 were applied to human skin cultures (25-30 mg/cm2 ) for a total of 72 h of treatment and exposed to oxidative stress. The generation of free radicals was semi-quantitatively assessed by measuring the fluorescence intensity of the deacetylation and oxidation of the probe dichlorofluorescein diacetate (DCFH-DA). In the second experiment, an ex vivo skin model (derived from patients undergoing facelift procedures) was used to assess elastin preservation. Three skin explants were topically subjected to the two formulations daily for 7 days. The skin was then prepared and fixed for immunofluorescent assessment after staining with CD44 and tropoelastin antibodies. Images were then analyzed using ImageJ. RESULTS: A full description of the different components selected for the new formulation is presented. In the first study, the experimental formulation performed with absolute equivalence to the comparator in its radical quenching capacity; both showed extremely effective antioxidant function. In the second study, the comparator negatively affected the existing elastin with areas of breakdown and diminished staining. In contrast, the new formulation showed good conservation of healthy elastin in all sections demonstrating elastin preservation. CONCLUSION: A new antioxidant formulation was carefully designed with multiple actives that show an equivalent antioxidant capacity to a leading product on the market. More importantly, the vitamin C component shows direct elastin conservation and improvement as opposed to the comparator, which had negative effects on elastin preservation. This is in keeping with little-known literature reports on vitamin C and its negative effects on elastin and validates the use of a sodium salt derivative, which appears to have protective effects on elastin. These findings support the overall regenerative extracellular matrix changes seen with TriHex® technology in other products.

Targeting Myofibroblasts as a Treatment Modality for Dupuytren Disease.

PURPOSE: Currently, no treatment corrects the contractile nature of Dupuytren myofibroblasts (DMFs) or prevents recurrence following surgery. Antifibrotic and proadipogenic growth factors are released when adipose-derived stem cells (ASCs) are cultured with platelet-rich plasma (PRP), a platelet concentration from whole blood. Reprograming myofibroblasts into adipocytes via growth factors is proposed as a powerful potential tool to target fibrosis. We aimed to assess whether the combination of ASCs and PRP reprograms DMFs into adipocytes in vitro and alters their contractile nature in vivo. METHODS: Normal human dermal fibroblasts (NHDFs) and DMFs from Dupuytren patients were isolated and cocultured with ASCs and PRP either alone or together. Adipocytes were detected by Oil Red O and perilipin staining. DMFs and NHDFs were transplanted into the forepaws of rats (Rowett Nude [rnu/rnu]) and treated with saline, PRP+ASCs, or collagenase Clostridium histolyticum (clinical comparison) 2 months later. After 2 weeks, the tissue was harvested and subjected to Masson trichrome staining, and collagen I and III and alpha-smooth muscle actin detection by immunohistochemistry. RESULTS: Myofibroblasts transform into adipocytes upon coculture with PRP+ASCs. DMFs show increased alpha-smooth muscle actin expression in vivo compared with NHDFs, which is significantly decreased after PRP+ASCs and collagenase Clostridium histolyticum treatments. DMFs induce collagen I and III expressions in rat paws compared with NHDFs, with a type III to I ratio increase. Treatment with PRP+ASC reduced the ratio, but collagenase Clostridium histolyticum did not. CONCLUSIONS: Treating DMFs with PRP+ASCs provides factors that induce myofibroblast to adipocyte transformation. This treatment reduces the contractile phenotype and fibrosis markers in vivo. Future studies should detail the mechanism of this conversion. CLINICAL RELEVANCE: The combination of PRP and ASCs to induce the differentiation of DMFs into adipocytes may serve to limit surgery to a percutaneous contracture release and biological injection, rather than a moderate or radical fasciectomy, and reduce the recurrence of Dupuytren contracture.

The New Threat to Abortion Access in the United States-The Comstock Act.

This Viewpoint explains the history of the Comstock Act, its use by those seeking to restrict abortion, and why it threatens abortion access in the US.

Combining Allograft Adipose and Fascia Matrix as an Off-the-Shelf Scaffold for Adipose Tissue Engineering Stimulates Angiogenic Responses and Activates a Proregenerative Macrophage Profile in a Rodent Model.

OBJECTIVE: Bioscaffolds for treating soft tissue defects have limitations. As a bioscaffold, allograft adipose matrix (AAM) is a promising approach to treat soft tissue defects. Previously, we revealed that combining superficial adipose fascia matrix with AAM, components of the hypodermis layer of adipose tissue, improved volume retention, adipogenesis, and angiogenesis in rats 8 weeks after it was implanted compared with AAM alone. Here, we modified the fascia matrix and AAM preparation, examined the tissue over 18 weeks, and conducted a deeper molecular investigation. We hypothesized that the combined matrices created a better scaffold by triggering angiogenesis and proregenerative signals. METHODS: Human AAM and fascia matrix were implanted (4 [1 mL] implants/animal) into the dorsum of male Fischer rats (6-8 weeks old; ~140 g) randomly as follows: AAM, fascia, 75/25 (AAM/fascia), 50/50, and 50/50 + hyaluronic acid (HA; to improve extrudability) (n = 4/group/time point). After 72 hours, as well as 1, 3, 6, 9, 12, and 18 weeks, graft retention was assessed by a gas pycnometer. Adipogenesis (HE), angiogenesis (CD31), and macrophage infiltration (CD80 and CD163) were evaluated histologically at all time points. The adipose area and M1/M2 macrophage ratio were determined using ImageJ. RNA sequencing (RNA-seq) and bioinformatics were conducted to evaluate pathway enrichments. RESULTS: By 18 weeks, the adipose area was 2365% greater for 50/50 HA (281.6 ± 21.6) than AAM (11.4 ± 0.9) (P < 0.001). The M1/M2 macrophage ratio was significantly lower for 50/50 HA (0.8 ± 0.1) than AAM (0.9 ± 0.1) at 6 weeks (16%; P < 0.05). This inversely correlated with adipose area (r = -0.6; P > 0.05). The RNA-seq data revealed that upregulated adipogenesis, angiogenesis, and macrophage-induced tissue regeneration genes were temporally different between the groups. CONCLUSIONS: Combining the fascia matrix with AAM creates a bioscaffold with an improved retention volume that supports M2 macrophage-mediated angiogenesis and adipogenesis. This bioscaffold is worthy of further investigation.

Deconstructing Allograft Adipose and Fascia Matrix: Fascia Matrix Improves Angiogenesis, Volume Retention, and Adipogenesis in a Rodent Model.

BACKGROUND: Autologous fat grafting is commonly used for soft-tissue repair (approximately 90,000 cases per year in the United States), but outcomes are limited by volume loss (20% to 80%) over time. Human allograft adipose matrix (AAM) stimulates de novo adipogenesis in vivo, but retention requires optimization. The extracellular matrix derived from superficial fascia, interstitial within the adipose layer, is typically removed during AAM processing. Thus, fascia, which contains numerous important proteins, might cooperate with AAM to stimulate de novo adipogenesis, improving long-term retention compared to AAM alone. METHODS: Human AAM and fascia matrix proteins (back and upper leg regions) were identified by mass spectrometry and annotated by gene ontology. A three-dimensional in vitro angiogenesis assay was performed. Finally, AAM and/or fascia (1 mL) was implanted into 6- to 8-week-old male Fischer rats. After 8 weeks, the authors assessed graft retention by gas pycnometry and angiogenesis (CD31) and adipocyte counts (hematoxylin and eosin) histologically. RESULTS: Gene ontology annotation revealed an angiogenic enrichment pattern unique to the fascia, including lactadherin, collagen alpha-3(V) chain, and tenascin-C. In vitro, AAM stimulated 1.0 ± 0.17 angiogenic sprouts per bead. The addition of fascia matrix increased sprouting by 88% (2.0 ± 0.12; P < 0.001). A similar angiogenic response (CD31) was observed in vivo. Graft retention volume was 25% (0.25 ± 0.13) for AAM, significantly increasing to 60% (0.60 ± 0.14) for AAM/fascia ( P < 0.05). De novo adipogenesis was 12% (12.4 ± 7.4) for AAM, significantly increasing to 51% (51.2 ± 8.0) for AAM/fascia ( P < 0.001) by means of adipocyte quantification. CONCLUSIONS: Combining fascia matrix with AAM improves angiogenesis and adipogenesis compared to AAM alone in rats. These preliminary in vitro and pilot animal studies should be further validated before definitive clinical adoption. CLINICAL RELEVANCE STATEMENT: When producing an off-the-shelf adipose inducing product by adding a connective tissue fascial component (that is normally discarded) to the mix of adipose matrix, vasculogenesis is increased and, thus, adipogenesis and graft survival is improved. This is a significant advance in this line of product.

Advances in Pigmentation Management: A Multipronged Approach.

BACKGROUND: Key cellular players regulating human skin pigmentation include melanocytes in the epidermis that synthesize melanin, neighboring keratinocytes that receive and distribute melanin in the upper layers, and fibroblasts in the dermis that affect overlying melanocytes and keratinocytes. In addition, endocrine factors from the blood supply (endothelial cells) and inflammation-related factors play a role. Thus, new strategies for affecting pigmentation need to consider these multiple cell lines to adequately cover various causes and disease processes associated with hyperpigmentation. METHODS: Pathophysiologic mechanisms and cellular pathways involved in melanogenesis were thoroughly reviewed with particular emphasis on the cellular interplay involved in the process. A complex system of interlinking and independent pathways was defined and described demonstrating differing pathways for altered pigmentary disorders - melasma associated with endothelial cell interactions; post inflammatory hyperpigmentation associated with keratinocyte inflammatory mediators (PGE2 in particular); and photodamage involving all 4 cell types. In vitro validation studies were then undertaken to define differing cell group gene expression profiles with selected peptides and other active agents. Melanocytic production of pigment was then tested with these agents to identify key potential players capable of limiting pigmentation. RESULTS: Hexapeptide-12 and lactoferrin (melanocytes), Hexapeptide-11 (in keratinocytes), and phosphatidylserine (endothelial cells) were identified as major inhibitors of melanogenesis based on their gene expression profiles. This was confirmed by secondary melanin production tests performed on melanocytic lines. Additional active agents were also identified as inhibitors of melanocytic production of melanin, and together, these constituents formed the basis for a novel formulation for use in pigmentary disorders. CONCLUSION: A comprehensive scientific narrative of the various facets relating to pigmentation has been presented including differing pathways affecting varied cell lines that effect pigment production. Based on this concept, actives were tested using gene expression studies as well as in vitro melanogenic model testing in different cell lines. Using this novel multi-faceted approach, we have selected and validated a series of active agents to be used in a formulation targeting the complex problem of hyperpigmentation. J Drugs Dermatol. 2022;21(11):1206-1220. doi:10.36849/JDD.7013.

Effects of a Topical Anti-aging Formulation on Skin Aging Biomarkers.

Objective: Following previous clinical trials, an antiaging product (Restorative Skin complex [RSC]; Alastin Skin Care Carlsbad, a Galderma company), was investigated for its effects on Klotho gene regulation, telomere length, and histological biopsy changes to provide a comprehensive picture of the mechanism and efficacy of its anti-aging effect. Methods: Neonatal human fibroblasts were used for telomere length studies to examine the effect of the full RSC formulation and the amino acid components Tripeptide-1 and Hexapeptide-12 (TriHex™) on these cellular aging mechanisms. In addition, RNA sequencing was conducted using human keratinocytes specifically investigating Klotho and related genes. This was supplemented by a clinical study using biopsy samples. Results: TriHex™ significantly upregulated the Klotho gene and related FGF23, FGFR1 and FOXO3B anti-aging genes. Significant telomere shortening reduction over control was demonstrated with the RSC formulation at four weeks and with TriHex™ at six weeks for all percentiles tested. Previous clinical studies demonstrated that the use of the antiaging regimen for 12 weeks produced a statistically significant improvement in scores for all evaluated parameters. Restaining of previous biopsy blocks from the clinical trial revealed positive ECM changes, stimulation of collagen, fibrillin, CD44 and elastin. Limitations: The study was limited by a relatively small numbers of patients in the clinical trial and the non-competitive nature of the trial. Conclusion: RSC anti-aging formulation and its TriHex™ components demonstrated significant reduction in telomere shortening, upregulation of Klotho and FOXO3 genes and biopsy validation of anti-aging efficacy. This new science supplements previous trials that demonstrated clinical efficacy of the formulation.

The End of Roe v. Wade.

The Supreme Court seems poised to overrule Roe v. Wade and hold that there is no constitutional right to choose abortion. The reversal of Roe seems to run counter to public opinion in the United States-while many favor restrictions, a clear majority do not want Roe reversed and favor access to abortion early in pregnancy. The current Court's apparent willingness to run the risk of political pushback has a complex history. Scholars have long described the Court as a countermajoritarian institution, but in practice, as historians have shown, the Court tends not to stray too far from popular opinion. For a Court bent on reversing Roe and tackling a long list of other divisive topic, concerns about institutional legitimacy no longer appear to be an effective check. A post-Roe Court may be more unplugged from popular opinion, with unpredictable results for the future of the democracy.

Designing topical hyaluronic acid technology-Size does matter .

INTRODUCTION: Hyaluronic acid (HA) plays an important role in cellular and extracellular matrix (ECM) homeostasis. Recent studies demonstrate that low molecular weight (MW) HA has pro-inflammatory characteristics while high MW HA is considered anti-inflammatory and regenerative. In formulating a topical HA product, the possibility of creating a focused high MW HA technology was posed, combining external surface high MW HA constituents with active agents promoting fibroblast production of high MW in the depths of the dermis. METHODS: Human dermal fibroblasts and keratinocytes were treated with various agents, and RNA sequencing (RNA-seq) was conducted to identify genes involved in HA synthesis. HA production by fibroblasts was assessed by collecting the culture supernatant, concentrating the protein, and conducting polyacrylamide gel electrophoresis (PAGE). The gel was stained with Stains-All to identify bands relative to known HA products of different MWs. Subsequently, the supernatants were treated with hyaluronidase to confirm the bands corresponded to HA. RESULTS: The RNA-seq results revealed a variety of agents upregulated HA-related genes. However, a potent upregulation of HA synthesis gene was observed by hexapeptide-11 in the keratinocytes and a newly identified proprietary octapeptide in the fibroblasts. PAGE demonstrated not only robust production of HA by octapeptide, but significantly, the HA produced was ~2 Mega Daltons in size. Octapeptide was the most potent stimulator among the tested agents. CONCLUSION: Comprehensive in vitro testing identified a group of active agents that stimulated high MW HA production. This novel approach to HA topical application with exclusively high MW HA production should maximize hydration capacity while encouraging regenerative activity within the ECM. Multi-center trials are underway.

Patient-Reported Satisfaction After Autologous Auricular Reconstruction in Patients with Microtia: A Systematic Review.

Importance: In a patient-centered field such as plastic surgery, patient-reported satisfaction can measure the success and value of surgery, since it is not uncommon for patient and surgeon assessments to differ. Currently, there is no standard for evaluating patient-reported satisfaction postauricular reconstruction. Objective: To systematically review the literature regarding patient-reported satisfaction postauricular reconstruction in microtia patients. Evidence Review: The databases MEDLINE, EMBASE, Cochrane, and Scopus were searched and preferred reporting items for systematic reviews and meta-analyses guidelines were followed. Studies documenting patient-reported satisfaction postauricular reconstruction in microtia patients were included. All techniques for ear reconstruction have been included in this review. Findings: Nineteen studies utilizing autologous reconstruction technique, comprising 3694 patients, met inclusion criteria. No standardized patient satisfaction assessment was used throughout the studies, indicating criteria variability to measure outcomes. Auricular substructure analysis highlighted lower patient satisfaction with the tragus and antitragus compared with the upper units. In addition, satisfaction depended on patient perception, not on a low surgical complication rate. Conclusions: There is a clear need to incorporate a standardized validated surgery-specific questionnaire related to patient satisfaction in the auricular reconstruction protocol.

Topical Skin Treatment and Its Influence on Surgical Healing: Review of Literature and Underlying Physiology.

TriHex Technology (Alastin Skincare, Carlsbad, CA) has been shown clinically to promote healing and outcomes post procedures and has been demonstrated clinically to improve lipid droplet dissolution and patient-reported outcomes post procedure. Histologically, the formulations have proven to regenerate collagen and elastin. The use of the technology to prepare the skin for surgical procedures combined with its use post procedure was assessed through clinical study outcomes, histological evidence, and gene expression analyses and demonstrated remodeling of the extracellular matrix (ECM), accelerating healing, and initiation of anti-inflammatory genes. While the improvement in clinical signs and outcomes has been validated, the changes taking place at a molecular level need to be explored. The interaction of cells (adipocytes, macrophages, fibroblasts) and the ECM proteins (collagen, elastin) secondary to the effects of the topical agent application are discussed. It appears that the manipulation of fat during body contouring surgery and the resultant adipocytolysis precipitates a molecular profile that can be positively directed toward hastened healing by using adjuvant topical applications as preconditioning prior to surgery and after the surgical procedure. Here, we review the literature and underlying physiology relating to these products and describe how interleukin 6 appears to be the primary facilitator of these effects.

An Analysis of Patient-Reported Recovery Outcomes of Topical Tripeptide/Hexapeptide Formulations Utilized in a Prospective Randomized Double-Blind Split Neck and Body Study.

BACKGROUND: Physicians strive to improve the postsurgical experience and optimize patient-reported recovery outcome measures (PROMs) following elective cosmetic surgical procedures. Our previous pilot feasibility study demonstrated that twice daily postoperative topical body treatment with tripeptide and hexapeptide (TransFORM Body Treatment with TriHex Technology [TFB, Alastin Skincare, Inc., Carlsbad, CA]) reduced PROMs of swelling, induration, soft tissue fibrosis, and pain as well as improved visible and palpable skin quality. OBJECTIVES: Evaluate whether adding a tripeptide/hexapeptide anhydrous gel (Regenerating Skin Nectar with TriHex Technology [RSN, Alastin Skincare, Inc., Carlsbad, CA]) pre- and post-procedure to the existing postsurgical regimen of TFB significantly improves 6 PROMs in patients undergoing neck and body contouring cosmetic surgical procedures. METHODS: Ten female patients underwent 15 neck and body contouring procedures and were blindly randomized to 1 of 2 topical treatment protocols (1 [TFB] and 2 [RSN/TFB]) pre- and post-procedure. Patient-reported scores of 5 skin parameters (skin discoloration, ecchymosis, edema, induration, and subcutaneous fibrous banding) and pain scores using the Visual Analog Scale were collected at 8 intervals for 12 weeks post-procedure. RESULTS: The treatment side that used both topicals showed significantly reduced scores of edema, induration, and subcutaneous fibrous banding compared with the side that only used 1 topical, on days 5-7 and 10-14 (P < 0.05). All patients observed slower soft tissue recovery on the side that was treated with TFB alone and opted to break the code and use both topical treatments. CONCLUSIONS: Patients had statistically significant improved patient-reported measures of skin edema, skin induration, and subcutaneous banding on the operated side that used both topicals.

Evaluating the Efficacy, Tolerability, and Outcomes of Topical Tripeptide/Hexapeptide Formulations Before and After Liposuction of the Medial Thighs.

Regenerating Skin Nectar with TriHex Technology (RSN) has been shown clinically to promote healing and outcomes post procedures. TransFORM Body Treatment with TriHex Technology (TFB) has demonstrated clinically to improve lipid droplet dissolution and patient-reported outcomes post procedure. Histologically, both have been proven to regenerate collagen and elastin. The objective is to evaluate postprocedural recovery, histological, and gene expression changes of medial thigh liposuction in participants using RSN and TFB on one thigh in comparison with a bland moisturizer on the other. Participants were randomized to apply RSN pre and post procedure and TFB post procedure to one thigh and a bland moisturizer to the other. After topical pretreatment, participants underwent bilateral medial thigh liposuction. Assessments included induration measurements, ultrasounds, blinded investigator assessments, participant assessments, photography, and biopsies for 10 weeks post procedure. Blinded investigator assessments of induration, edema, and subcutaneous fibrous banding had less severity at weeks 1, 2, and 4 on the RSN/TFB thigh, corresponding with induration measurements. Ultrasound images showed less fluid infiltration, edema, and induration on the RSN/TFB side over the bland moisturizer at 2 weeks. Gene expression confirmed a hastened inflammatory phase converting more rapidly to the anti-inflammatory regenerative healing environment with evidence of extracellular remodeling only present on the RSN/TFB side at week 4, and histological biopsies demonstrated improved collagenesis and elastogenesis. RSN used before surgical procedures combined with RSN and TFB post procedure has demonstrated remodeling of the extracellular matrix, accelerating healing, and initiation of anti-inflammatory genes.

Improving In Vitro Cartilage Generation by Co-Culturing Adipose-Derived Stem Cells and Chondrocytes on an Allograft Adipose Matrix Framework.

BACKGROUND: Microtia is an inherited condition that results in varying degrees of external ear deformities; the most extreme form is anotia. Effective surgical reconstruction techniques have been developed. However, these usually require multistage procedures and have other inherent disadvantages. Tissue engineering technologies offer new approaches in the field of external ear reconstruction. In this setting, chondrocytes are cultured in the laboratory with the aim of creating bioengineered cartilage matrices. However, cartilage engineering has many challenges, including difficulty in culturing sufficient chondrocytes. To overcome these hurdles, the authors propose a novel model of cartilage engineering that involves co-culturing chondrocytes and adipose-derived stem cells on an allograft adipose-derived extracellular matrix scaffold. METHODS: Auricular chondrocytes from porcine ear were characterized. Adipose-derived stem cells were isolated and expanded from human lipoaspirate. Then, the auricular chondrocytes were cultured on the allograft adipose matrix either alone or with the adipose-derived stem cells at different ratios and examined histologically. RESULTS: Cartilage induction was most prominent when the cells were co-cultured on the allograft adipose matrix at a ratio of 1:9 (auricular chondrocyte-to-adipose-derived stem cell ratio). Furthermore, because of the xenogeneic nature of the experiment, the authors were able to determine that the adipose-derived stem cells contributed to chondrogenesis by means of a paracrine stimulation of the chondrocytes. CONCLUSIONS: In this situation, adipose-derived stem cells provide sufficient support to induce the formation of cartilage when the number of auricular chondrocytes available is limited. This novel model of cartilage engineering provides a setting for using the patient's own chondrocytes and adipose tissue to create a customized ear framework that could be further used for surgical reconstruction.

Slug regulates the Dll4-Notch-VEGFR2 axis to control endothelial cell activation and angiogenesis.

Slug (SNAI2), a member of the well-conserved Snail family of transcription factors, has multiple developmental roles, including in epithelial-to-mesenchymal transition (EMT). Here, we show that Slug is critical for the pathological angiogenesis needed to sustain tumor growth, and transiently necessary for normal developmental angiogenesis. We find that Slug upregulation in angiogenic endothelial cells (EC) regulates an EMT-like suite of target genes, and suppresses Dll4-Notch signaling thereby promoting VEGFR2 expression. Both EC-specific Slug re-expression and reduced Notch signaling, either by γ-secretase inhibition or loss of Dll4, rescue retinal angiogenesis in SlugKO mice. Conversely, inhibition of VEGF signaling prevents excessive angiogenic sprouting of Slug overexpressing EC. Finally, endothelial Slug (but not Snail) is activated by the pro-angiogenic factor SDF1α via its canonical receptor CXCR4 and the MAP kinase ERK5. Altogether, our data support a critical role for Slug in determining the angiogenic response during development and disease.