Graft Vascularization Research Articles

CXCL13 promote angiogenesis by recruiting M2 macrophages and endothelial progenitor cells in beige adipose grafts

AbstractFat grafting is an emerging clinical technique to address soft tissue deficiencies. This study investigates whether the secretory function of beige adipose tissue(BeigeAT) grafts is involved in promoting soft tissue regeneration in fat grafting. In this study, mice were randomly divided into white adipose tissue (WAT) and BeigeAT groups. Each type of adipose tissue (0.3 mL) was transplanted into the respective groups, and samples were harvested at 2, 4, and 12 week. Subsequently, mice were further divided into three groups, BeigeAT group, BeigeAT with CXCL13 treatment group, and BeigeAT with TAK‐779 treatment group, to investigate the role of CXCL13 in BeigeAT transplants. Graft retention rate, vascularization, and fibrosis levels were compared among the groups. Compared to WAT transplants, BeigeAT transplants exhibited moderate inflammation, enhanced revascularization, reduced fibrosis, and increased infiltration of M2 macrophages and endothelial progenitor cells in the early stages following fat grafting. CXCL13 expression was significantly higher in BeigeAT transplants at 2, 4, and 12 week post‐grafting. Additionally, modulation of CXCL13 expression affected the infiltration of M2 macrophages and endothelial progenitor cells. However, BeigeAT transplants exhibited superior retention rates compared to BeigeAT CXCL13 groups and BeigeAT TAK‐779 groups after 12 weeks of fat grafting. BeigeAT transplants achieve improved retention rates through CXCL13‐induced infiltration of M2 macrophages and endothelial progenitor cells.

A decade's experience of robotic buccal ureteroplasty for post ureteroscopic laser lithotripsy induced strictures—Should this be the new standard?

ObjectiveTo present the surgical technique of robotic buccal ureteroplasty for strictures after laser lithotripsy and its outcomes. MethodsThis was a retrospective study conducted at the Department of Urology at Apollo Hospitals, Chennai, India from October 2012 to October 2022. Indications for surgery included worsening hydronephrosis, declining renal function, and recurrent urinary tract infections with obstruction. Apart from liberal exposure of the stricture, we stress upon the use of indocyanine green to assess vascularity and quilting of the graft to bare area of psoas muscle to increase the graft vascularity. ResultsAmong the 15 patients, ureteropelvic junction strictures were observed in eight (53.3 %), while five (33.3 %) had proximal stricture, and two (13.3 %) had mid-ureteral stricture. Notably, eight of the 15 (53.3 %) patients had previous unsuccessful double-J stenting. The median stricture length was 3.5 cm (range: 2–5 cm), with a mean operative time of 167 min (range: 126–214 min) and estimated blood loss of 140 mL (range: 40–200 mL). After a median follow-up of 12 months (range: 4–32 months), 13 out of 15 (86.7 %) patients showed significant improvement in their follow-up functional scans. ConclusionRobotic buccal ureteroplasty is a very effective technique for the management of laser-induced ureteral strictures with good long-term results and minimum morbidity. The results are comparable irrespective of previous failed stenting.

Challenges and Opportunities in Developing Tracheal Substitutes for the Recovery of Long-Segment Defects.

Tracheal resection and reconstruction procedures are necessary when stenosis, tracheomalacia, tumors, vascular lesions, or tracheal injury cause a tracheal blockage. Replacement with a tracheal substitute is often recommended when the trauma exceeds 50% of the total length of the trachea in adults and 30% in children. Recently, tissue engineering and other advanced techniques have shown promise in fabricating biocompatible tracheal substitutes with physical, morphological, biomechanical, and biological characteristics similar to native trachea. Different polymers and biometals are explored. Even with limited success with tissue-engineered grafts in clinical settings, complete healing of tracheal defects remains a substantial challenge due to low mechanical strength and durability of the graft materials, inadequate re-epithelialization and vascularization, and restenosis. This review has covered a range of reconstructive and regenerative techniques, design criteria, the use of bioprostheses and synthetic grafts for the recovery of tracheal defects, as well as the traditional and cutting-edge methods of their fabrication, surface modification for increased immuno- or biocompatibility, and associated challenges.

Clinical profile and outcomes of rejection after deep anterior lamellar keratoplasty in keratoconus.

To report the clinical features and management outcomes of rejection after deep anterior lamellar keratoplasty (DALK). The clinical features, indications, predisposing risk factors, management, and outcome of six eyes of six patients with rejection after DALK were analyzed retrospectively. The median time of rejection from the day of surgery was 12 (range 3-36) months. Median duration of symptoms was 4 (range 2-28) days. The indication for DALK was keratoconus in all eyes. The clinical features at presentation included graft haze, vascularization, and melt at the graft-host junction. The risk factors noted were noncompliance to steroids in all eyes, vernal conjunctivitis (four eyes), and eccentric graft (one eye). The rejection episode reversed with topical steroids in all eyes and intravenous methylprednisolone in one eye. One eye developed secondary fungal keratitis after initial recovery and one eye had a second episode of rejection 3 months later, which resulted in progressive vessels and lipid keratopathy in the visual axis. The median best corrected visual acuity was 20/40 (range 20/30-20/200). Severe stromal rejection can present with graft melt. Repeat episodes of rejection can occur on sudden cessation of topical steroids. Prompt recognition of clinical signs and symptoms with timely management helps in quick reversal of the rejection episode. Reversal of graft rejection results in good visual outcomes.

Attenuated angiogenesis and macrophage infiltration during adipose tissue regeneration in a megavolume human fat grafting nude mouse model.

Survival and regeneration mechanisms of large (>250 mL) fat grafts remain incompletely understood. In fat grafts from volunteers with megavolume fat transfer breast augmentation, neovascularization and inflammatory cell infiltration decreased within 7 days according to histological analysis. We further investigated this phenomenon using a nude mouse model. To simulate clinical contexts, chambers containing 1 mL human fat were implanted into nude mice. Chambers allowed selective transfer of tissue fluid from recipient nude mice into chambers, but not capillaries or macrophages. Seven days later, fat was removed from the chamber and reimplanted into a new nude mouse in the open-chambered fat group (OCFG, n=45). Adipose samples from volunteers and explanted grafts from OCFG were subjected to histological analyses. Graft weight, vascularization, and immune response were also compared between the OCFG and conventional direct fat grafting (control group (CG)). Percent tissue integrity, percent fibrosis, adipocyte viability, and neovascularization did not significantly differ between volunteer samples and OCFG grafts at day 7. On day 90, OCFG retention rate was decreased relative to CG and the fibrosis area was larger in the OCFG than in the CG. However, the macrophage and capillary counts were lower in the OCFG group relative to CG at days 7 and 14 after transplantation. The present study provides histological analyses of megavolume fat grafts sampled from clinical breast augmentation tissues and a xenograft nude mouse model. However, these preliminary results in a small clinical cohort should be further assessed in large allogeneic animal models.

DEVELOPING NEXT-GENERATION INJECTABLE ADIPOSE TISSUE GRAFTS FOR SOFT-TISSUE RECONSTRUCTION

IntroductionAutologous fat grafting has favourable potential as a regenerative strategy and is the current gold-standard to repair large contour defects, as needed in breast reconstruction after mastectomy and traumatic soft tissue reconstruction. Clinically, there is a limit on the volume of lipoaspirate which can be utilised to repair a soft-tissue defect. Surgical complications are the result of poor structural fidelity of lipoaspirate and graft resorption as a filling material and are hindered further by poor graft vascularisation. This study aims to develop injectable lipoaspirate-derived adipose tissue grafts with enhanced biologically and clinically-admissible structural and functional properties adopting light photocrosslinking of unmodified lipoaspirate.MethodsPatient-derived lipoaspirate was harvested and crosslinked using novel photoinitiator and exposure to visible light (wavelength 450nm) in surgery, establishing bonds between extracellular matrix (ECM) proteins within the material. The degree of crosslinking was tuned (photoinitiator concentration, light exposure, light intensity) and covalent bond formation measured using mass spectrometry. To predict patient response, SWATH-MS was used to identify differences in patient ECM and crosslinked grafts were implanted in vivo using a subcutaneous mouse model. Functional vessel formation and resorption were quantified using micro-CT and tissue-remodelling was assessed via histology.ResultsThere was an increase in the relative abundance of covalent bonds present with increasing degree of crosslinking. When injected, crosslinked lipoaspirate had better shape fidelity compared with native lipoaspirate – demonstrated by a smaller fibre diameter. Crosslinked lipoaspirate remained viable over long term culture and resulted in more predictable resorption profiles when implanted in vivo.ConclusionsThe crosslinking approach described here is tunable and functional across different patient samples. Improving the structural properties of lipoaspirate through minimal manipulation has clinical utility for the delivery of grafts with higher shape fidelity and therefore increased graft survival when implanted.

THE INTERPLAY OF ANGIOGENESIS AND OSTEOGENESIS FOR BONE REGENERATION

Bone regeneration is an area of acute medical need, but its clinical success is hampered by the need to ensure rapid vascularization of osteogenic grafts. Vascular Endothelial Growth Factor (VEGF) is the master regulator of vascular growth and during bone development angiogenesis and osteogenesis are physiologically coupled through so-called angiocrine factors produced by blood vessels. However, how to exploit this process for therapeutic bone regeneration remains a challenge (1).Here we will describe recent work aiming at understanding the cross-talk between vascular growth and osteogenesis under conditions relevant for therapeutic bone regeneration. To this end we take advantage of a unique platform to generate controlled signalling microenvironments, by the covalent decoration of fibrin matrices with tunable doses and combinations of engineered growth factors. The combination of human osteoprogenitors and hydroxyapatite in these engineered fibrin matrices provides a controlled model to investigate how specific molecular signals regulate vascular invasion and bone formation in vivo. In particular, we found that:Controlling the distribution of VEGF protein in the microenvironment is key to recapitulate its physiologic function to couple angiogenesis and osteogenesis (2);Such coupling is exquisitely dependent on VEGF dose and on a delicate equilibrium between opposing effects. A narrow range of VEGF doses specifically activates Notch1 signaling in invading blood vessels, inducing a pro-osteogenic functional state called Type H endothelium, that promotes differentiation of surrounding mesenchymal progenitors. However, lower doses are ineffective and higher ones paradoxically inhibit both vascular invasion and bone formation (Figure 1) (3);Semaphorin3a (Sema3a) acts as a novel pro-osteogenic angiocrine factor downstream of VEGF and it mediates VEGF dose-dependent effects on both vascular invasion and osteogenic progenitor stimulation.In conclusion, vascularization of osteogenic grafts is not simply necessary in order to enable progenitor survival. Rather, blood vessels can actively stimulate bone regeneration in engineered grafts through specific molecular signals that can be harnessed for therapeutic purposes.Acknowledgements: This work was supported in part by the European Union Horizon 2020 Program (Grant agreement 874790 – cmRNAbone).For any figures and tables, please contact the authors directly.

A coaxial electrospun mat coupled with piezoelectric stimulation and atorvastatin for rapid vascularized bone regeneration.

The repair of critical bone defects caused by various clinical conditions needs to be addressed urgently, and the regeneration of large bone defects depends on early vascularization. Therefore, enhanced vascularization of artificial bone grafts may be a promising strategy for the regeneration of critical-sized bone defects. Taking into account the importance of rapid angiogenesis during bone repair and the potential of piezoelectric stimulation in promoting bone regeneration, novel coaxial electrospun mats coupled with piezoelectric materials and angiogenic drugs were fabricated in this study using coaxial electrospinning technology, with a shell layer loaded with atorvastatin (AVT) and a core layer loaded with zinc oxide (ZnO). AVT was used as an angiogenesis inducer, and piezoelectric stimulation generated by the zinc oxide was used as an osteogenesis enhancer. The multifunctional mats were characterized in terms of morphology, core-shell structure, piezoelectric properties, drug release, and mechanical properties, and their osteogenic and angiogenic capabilities were validated in vivo and ex vivo. The results revealed that the coaxial electrospun mats exhibit a porous surface morphology and nanofibers with a core-shell structure, and the piezoelectricity of the mats improved with increasing ZnO content. Excellent biocompatibility, hydrophilicity and cell adhesion were observed in the multifunctional mats. Early and rapid release of AVT in the fibrous shell layer of the mat promoted angiogenesis in human umbilical vascular endothelial cells (HUVECs), whereas ZnO in the fibrous core layer harvested bioenergy and converted it into electrical energy to enhance osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs), and both modalities synergistically promoted osteogenesis and angiogenesis. Furthermore, optimal bone regeneration was achieved in a model of critical bone defects in the rat mandible. This osteogenesis-promoting effect was induced by electrical stimulation via activation of the calcium signaling pathway. This multifunctional mat coupling piezoelectric stimulation and atorvastatin promotes angiogenesis and bone regeneration, and shows great potential in the treatment of large bone defects.

Transplantation and Noninvasive Longitudinal In Vivo Imaging of Parathyroid Cells: A Proof-of-Concept Study.

The parathyroid cell is a vital regulator of extracellular calcium levels, operating through the secretion of parathyroid hormone (PTH). Despite its importance, the regulation of PTH secretion remains complex and not fully understood, representing a unique interplay between extracellular and intracellular calcium, and hormone secretion. One significant challenge in parathyroid research has been the difficulty in maintaining cells ex vivo for in-depth cellular investigations. To address this issue, we introduce a novel platform for parathyroid cell transplantation and noninvasive in vivo imaging using the anterior chamber of the eye as a transplantation site. We found that parathyroid adenoma tissue transplanted into the mouse eye engrafted onto the iris, became vascularized, and retained cellular composition. Transplanted animals exhibited elevated PTH levels, indicating a functional graft. With in vivo confocal microscopy, we were able to repetitively monitor parathyroid graft morphology and vascularization. In summary, there is a pressing need for new methods to study complex cellular processes in parathyroid cells. Our study provides a novel approach for noninvasive in vivo investigations that can be applied to understand parathyroid physiology and pathology under physiological and pathological conditions. This innovative strategy can deepen our knowledge on parathyroid function and disease.

Correlation Analysis of the Anatomical Structures Related to Maxillary Sinus Augmentation

Aims: Preoperative evaluation of maxillary sinus anatomy is crucial to minimize procedural complications. The aim of this study was to assess the anatomical structures associated with sinus augmentation and investigate the correlation between these structures. Materials and Methods: This retrospective study included cone-beam computed tomography scans of patients referred for the reconstruction of the posterior maxilla with dental implants. The intraosseous anastomosis (PIA) and septa were evaluated on the images. Lateral wall thickness (LWT), the diameter of the PIA (DIA), the vertical distance of the PIA to the sinus floor (DSF), and sinus floor angle (SFA) were also measured. Results: A total of 250 sinuses were examined. PIA was detected in 46.8% of the sinuses. The mean SFA value was 77.11° ±11.11° (range 48.25°–112.33°). The LWT ranged from 0.63 to 10.23 mm with a mean value of 1.35 ± 0.79 mm. Of 250 sinuses, 82 (32.8%) showed septa. A strong negative correlation was found between SFA and PIA detection (r = 0.98, P = 0.008), SFA and DSF (r = 0.99, P = 0.000), and SFA and septa (r = 0.98, P = 0.000). LWT showed a positive correlation with DIA (r = 0.72, P = 0.082), although not statistically significant. Conclusions: The relationships highlight the combined effect of the structures on membrane perforation. As this makes the lateral window approach more problematic, the surgeon may seek minimally invasive approaches. Moreover, the strong correlation of SFA-PIA-DSF may significantly affect graft vascularization and needs to be evaluated with clinical studies.

Comparison of two graft procedures in a bilateral sinus lift by MRI and histomorphometric analysis: a case report

Magnetic resonance imaging (MRI) was shown to be a viable method for graft healing evaluation. Platelet-rich fibrin (PRF) was found to speed up bone graft healing process. Sinus lift surgery outcomes after healing period are usually performed with computerized tomography that is not capable to describe graft vascularization and exposes patient to ionizing radiation. The objective of this study is to propose contrast-enhanced magnetic resonance imaging (CE-MRI) as a promising method for the in vivo assessment of sinus lift grafting procedures. A bilateral sinus augmentation surgery was performed. Left sinus was grafted only with bovine deproteinized bone mixed in a 1:1 ratio with autologous bone, in the right sinus, the same biomaterials with the addition of platelet-rich fibrin (PRF) were applied. CE-MRI was performed to evaluate angiogenesis before surgery and at 11, 25, 53, and 104 days after surgery. At 6 months (T0) and after 10 years (T1), before dental implants insertion, bone biopsies were performed and analysed quantitatively. Left sinus graft showed a centripetal pattern of angiogenesis, with the central region remaining unvascularized at 104 days post-surgery. Right side showed a wider and homogeneous vascularization from 25 days after surgery. At T0 new bone formation was only peripheral in the left sinus, whereas it developed both peripherally and through biomaterial in the right sinus. At T1 particles of biomaterial were still present in left sinus, while in right sinus they were not. CE-MRI offers quantitative parameters to evaluate vascularization of biomaterials. The addition of PRF promotes an early development of a widespread vascular system.

Engineering 3D-Printed Bioresorbable Scaffold to Improve Non-Vascularized Fat Grafting: A Proof-of-Concept Study.

Autologous fat grafting is the gold standard for treatment in patients with soft-tissue defects. However, the technique has a major limitation of unpredictable fat resorption due to insufficient blood supply in the initial phase after transplantation. To overcome this problem, we investigated the capability of a medical-grade poly L-lactide-co-poly ε-caprolactone (PLCL) scaffold to support adipose tissue and vascular regeneration. Deploying FDM 3D-printing, we produced a bioresorbable porous scaffold with interconnected pore networks to facilitate nutrient and oxygen diffusion. The compressive modulus of printed scaffold mimicked the mechanical properties of native adipose tissue. In vitro assays demonstrated that PLCL scaffolds or their degradation products supported differentiation of preadipocytes into viable mature adipocytes under appropriate induction. Interestingly, the chorioallantoic membrane assay revealed vascular invasion inside the porous scaffold, which represented a guiding structure for ingrowing blood vessels. Then, lipoaspirate-seeded scaffolds were transplanted subcutaneously into the dorsal region of immunocompetent rats (n = 16) for 1 or 2 months. The volume of adipose tissue was maintained inside the scaffold over time. Histomorphometric evaluation discovered small- and normal-sized perilipin+ adipocytes (no hypertrophy) classically organized into lobular structures inside the scaffold. Adipose tissue was surrounded by discrete layers of fibrous connective tissue associated with CD68+ macrophage patches around the scaffold filaments. Adipocyte viability, assessed via TUNEL staining, was sustained by the presence of a high number of CD31-positive vessels inside the scaffold, confirming the CAM results. Overall, our study provides proof that 3D-printed PLCL scaffolds can be used to improve fat graft volume preservation and vascularization, paving the way for new therapeutic options for soft-tissue defects.

Low-level laser therapy combined with scleral graft transplantation in the treatment of contracted socket: a clinical study

ObjectiveTo analyse the efficacy of the therapeutic use of low-level laser therapy (LLLT) on the tissue repair process of allogeneic scleral grafts in patients with contracted sockets by analysing the speed of graft vascularisation and fornice depth of contraction percentage.MethodsA retrospective chart review was performed from April 2015 to April 2021 including 39patients with socket contraction. Allogeneic scleral grafts were used to repair the sockets in all patients. They were randomly enrolled into two groups. The laser group included 18 patients treated with LLLT after the surgery, whereas the control group included 21 patients without LLLT after the surgery who healed naturally. The LLLT equipment used in the research had a wavelength of 650 nm, 10 mW power, and 3.8 J/cm2 dosimetry, and the procedure was performed once daily for 5 min over 7 days, beginning 1 week postoperatively. All patients were followed up over 6 months to examine the changes in the size of the area of the non-vascularised graft and upper and inferior fornice depth.ResultsThe laser group presented a significantly increased speed of conjunctival vascularisation compared with the control group (P = 0.003). The fornice depth of contraction percentage was more apparent in the control group than that in the laser group (P = 0.000).ConclusionLLLT accelerates conjunctival vascularisation, stimulates conjunctival incision healing within a short period, shortens the tissue repair process, reduces the local inflammatory response, and causes no significant shrinkage of the conjunctival sac.

Perspectives on the Current State of Bioprinted Skin Substitutes for Wound Healing.

Human skin is particularly vulnerable to external damaging influences such as irradiation, extreme temperatures, chemical trauma, and certain systemic diseases, which reduce the skin's capacity for regeneration and restoration and can possibly lead to large-scale skin defects. To restore skin continuity in severe cases, surgical interventions such as the transplantation of autologous tissue are needed. Nevertheless, the coverage of larger skin defects caused by severe third-grade burns or extensive irradiation therapy is limited due to the depletion of uninjured autologous tissue. In such cases, many of the patient's epidermal cells can become available using biofabricated skin grafts, thereby restoring the skin's vital functions. Given the limited availability of autologous skin grafts for restoring integrity in large-scale defects, using bioprinted constructs as skin graft substitutes could offer an encouraging therapeutic alternative to conventional therapies for large-scale wounds, such as the transplantation of autologous tissue. Using layer-by-layer aggregation or volumetric bioprinting, inkjet bioprinting, laser-assisted bioprinting, or extrusion-based bioprinting, skin cells are deposited in a desired pattern. The resulting constructs may be used as skin graft substitutes to accelerate wound healing and reconstitute the physiological functions of the skin. In this review, we aimed to elucidate the current state of bioprinting within the context of skin tissue engineering and introduce and discuss different bioprinting techniques, possible approaches and materials, commonly used cell types, and strategies for graft vascularization for the production of bioprinted constructs for use as skin graft substitutes.

Unveiling pro-angiogenesis and drug delivery using dual-bio polymer with bio-ceramic based nanocomposite hydrogels

In regenerative medicine, blood vessel development is of utmost importance as it enables the restoration of blood flow to tissues, and facilitate rapid vascularization in clinical tissue-engineered grafts. Herein, we fabricate the nanocomposite hydrogels from BG (clinophosinaite), alginate, Polyethylene glycol (PEG) and Dexamethasone (DEX) for the dual applications of drug delivery and angiogenesis assay. The hydrogels were fabricated through cross-linking approach and termed as alginate/PEG (A), alginate/PEG/clinophosinaite (AC), and alginate/PEG/clinophosinaite/DEX (ACD) that further subjected to structural characterization, using powder X-ray diffraction, and fourier-transform infrared spectroscopy. Porous nanostructures and sheets were imaged using field emission scanning electron microscopy (FESEM), which aid in nutrient and oxygen transport to support angiogenesis. The nanocomposite hydrogels evidently demonstrated good hemocompatibility and fully hydrophilic (30.20°). By means of liquid displacement technique, the nanocomposite hydrogel achieves 47% of porosity with the compressive strength about 0.04 MPa. In alginate/PEG/clinophosinaite and alginate/PEG/clinophosinaite/DEX systems, water absorption capacity reached 85% in 6 h and maintained 90% retention after 12 h. Further, leachable tests revealed that the hydrogel had not deformed even after 24 h. In vitro drug release studies evidently divulge sustainable delivery of DEX from alginate/PEG/clinophosinaite/DEX hydrogel with superior characteristics for drug release. The angiogenesis assay also evidently revealed that the AC and ACD hydrogels, demonstrated higher angiogenic properties with, promoted blood vessel development.

Actuated tissue engineered muscle grafts restore functional mobility after volumetric muscle loss

Damage that affects large volumes of skeletal muscle tissue can severely impact health, mobility, and quality-of-life. Efforts to restore muscle function by implanting tissue engineered muscle grafts at the site of damage have demonstrated limited restoration of force production. Various forms of mechanical and biochemical stimulation have been shown to have a potentially beneficial impact on graft maturation, vascularization, and innervation. However, these approaches yield unpredictable and incomplete recovery of functional mobility. Here we show that targeted actuation of implanted grafts, via non-invasive transcutaneous light stimulation of optogenetic engineered muscle, restores motor function to levels similar to healthy mice 2 weeks post-injury. Furthermore, we conduct phosphoproteomic analysis of actuated engineered muscle in vivo and in vitro to show that repeated muscle contraction alters signaling pathways that play key roles in skeletal muscle contractility, adaptation to injury, neurite growth, neuromuscular synapse formation, angiogenesis, and cytoskeletal remodeling. Our study uncovers changes in phosphorylation of several proteins previously unreported in the context of muscle contraction, revealing promising mechanisms for leveraging actuated muscle grafts to restore mobility after volumetric muscle loss.

Vascularization of the adult mouse lung grafted onto the chick chorioallantoic membrane

In the later stages of angiogenesis, the vascular sprout transitions into a functional vessel by fusing with a target vessel. Although this process appears to routinely occur in embryonic tissue, the biologic rules for sprout fusion and lumenization in adult regenerating tissue are unknown. To investigate this process, we grafted portions of the regenerating post-pneumonectomy lung onto the chick chorioallantoic membrane (CAM). Grafts from all 4 lobes of the post-pneumonectomy right lung demonstrated peri-graft angiogenesis as reflected by fluorescent plasma markers; however, fluorescent microsphere perfusion primarily occurred in the lobe of the lung that is the dominant site of post-pneumonectomy angiogenesis—namely, the cardiac lobe. Vascularization of the cardiac lobe grafts was confirmed by active tissue growth (p < .05). Functional vascular connections between the cardiac lobe and the CAM vascular network were demonstrated by confocal fluorescence microscopy as well as corrosion casting and scanning electron microscopy (SEM). Bulk transcriptional profiling of the cardiac lobe demonstrated the enhanced expression of many genes relative to alveolar epithelial cell (CD11b−/CD31−) control cells, but only the upregulation of Ereg and Fgf6 compared to the less well-vascularized right upper lobe. The growth of actively regenerating non-neoplastic adult tissue on the CAM demonstrates that functional lumenization can occur between species (mouse and chick) and across the developmental spectrum (adult and embryo).

Postkeratoplasty Corneal Plaques: A Case Series.

To assess the risk factors and management of corneal plaques formed after keratoplasty. In this retrospective study, medical records of all eyes with plaques formed on top of corneal grafts performed in the period between January 2014 and January 2022 were reviewed. The retrieved data included prekeratoplasty corneal pathology, ocular risk factors, operative data and complications, plaque management, and chemical composition of the plaques using infrared spectrometer. Thirteen eyes were included in this study. Predisposing ocular comorbidities included ocular surface disorders with variable degrees of dry eye in nine patients, rheumatoid arthritis in three patients, history of herpetic keratitis in two eyes, and cicatrizing conjunctivitis in two patients. Surgical excision and amniotic membrane transplantation (AMT) were performed in 12 eyes. Postoperatively, five eyes showed recurrence after excision, two eyes developed graft vascularization and scarring, and one eye showed persistent epithelial defect and graft scarring, whereas four eyes showed complete epithelialization with mild haze. Rekeratoplasty and AMT were performed in two eyes with no plaque recurrence. Chemical analysis using infrared spectrometry showed that the plaques consisted of ammonium magnesium phosphate and calcium phosphate carbonate in 9 (75%) cases and pure mucus in 3 (25%) cases. Postkeratoplasty corneal plaque formation is an underestimated complication of keratoplasty that may occur after persistent epithelial defects. Ocular surface disorders are the primary predisposing risk factors. In our experience, the prognosis after medical treatment or surgical scraping is guarded, and regrafting can be the only solution to restore graft clarity.

Fatter Is Better: Boosting the Vascularization of Adipose Tissue Grafts.

Adipose tissue resorption after fat grafting is a major drawback in plastic and reconstructive surgery, which is primarily caused by the insufficient blood perfusion of the grafts in the initial phase after transplantation. To overcome this problem, several promising strategies to boost the vascularization and, thus, increase survival rates of fat grafts have been developed in preclinical studies in recent years. These include the angiogenic stimulation of the grafts by growth factors and botulinum neurotoxin A, biologically active gels, and cellular enrichment, as well as the physical and pharmacological stimulation of the transplantation site. To transfer these approaches into future clinical practice, it will be necessary to establish standardized procedures for their safe application in humans. If this succeeds, the surgical outcomes of fat grafting may be markedly improved, resulting in a significant reduction of the physical and psychological stress for the patients.

Biomimetic in situ tracheal microvascularization for segmental tracheal reconstruction in one-step.

Formation of functional and perfusable vascular network is critical to ensure the long-term survival and functionality of the engineered tissue tracheae after transplantation. However, the greatest challenge in tracheal-replacement therapy is the promotion of tissue regeneration by rapid graft vascularization. Traditional prevascularization methods for tracheal grafts typically utilize omentum or muscle flap wrapping, which requires a second operation; vascularized segment tracheal orthotopic transplantation in one step remains difficult. This study proposes a method to construct a tissue-engineered tracheal graft, which directly forms the microvascular network after orthotopic transplantation in vivo. The focus of this study was the preparation of a hybrid tracheal graft that is non-immunogenic, has good biomechanical properties, supports cell proliferation, and quickly vascularizes. The results showed that vacuum-assisted decellularized trachea-polycaprolactone hybrid scaffold could match most of the above requirements as closely as possible. Furthermore, endothelial progenitor cells (EPCs) were extracted and used as vascularized seed cells and seeded on the surfaces of hybrid grafts before and during the tracheal orthotopic transplantation. The results showed that the microvascularized tracheal grafts formed maintained the survival of the recipient, showing a satisfactory therapeutic outcome. This is the first study to utilize EPCs for microvascular construction of long-segment trachea in one-step; the approach represents a promising method for microvascular tracheal reconstruction.