The reconstruction of posterior lamellar eyelid defects remains a significant challenge in clinical practice due to anatomical complexity, specialized function, and aesthetic concerns. The ideal substitute for the posterior lamellar should replicate the native tarsoconjunctival tissue, providing both mechanical support for the eyelids and a smooth surface for the globe after implantation. In this study, we present an innovative approach utilizing tissue-engineered cartilage (TEC) grafts generated from rabbit auricular chondrocytes and a commercialized type I collagen sponge to reconstruct critical-sized posterior lamellar defects in rabbits. The TEC grafts demonstrated remarkable mechanical strength and maintained a stable cartilaginous phenotype both in vitro and at 6 months post-implantation in immunodeficient mice. When employed as autografts to reconstruct tarsal plate defects in rabbits' upper eyelids, these TEC grafts successfully restored normal eyelid morphology, facilitated smooth eyelid movement, and preserved the histological structure of the conjunctival epithelium. When applied in bilayered tarsoconjunctival defect reconstruction, these TEC grafts not only maintained the normal contour of the upper eyelid but also supported conjunctival epithelial cell migration and growth from the defect margin towards the centre. These findings highlight that auricular chondrocyte-based TEC grafts hold great promise as potential candidates for clinical posterior lamellar reconstruction. The complex structure and function of the posterior lamellar eyelid continue to be significant challenges for clinical reconstructive surgeries. In this study, we utilized autologous auricular chondrocyte-based TEC grafts for posterior lamellar eyelid reconstruction in a preclinical rabbit model. The TEC grafts exhibited native cartilaginous histomorphology and comparable mechanical strength to those of the native human tarsal plate. In rabbit models with either tarsal plate defects alone or bilayered tarsoconjunctival defects, TEC grafts successfully restored the normal eyelid contour and movement, as well as supported preservation and growth of conjunctival epithelium. This is the first study to demonstrate autologous TEC grafts can be employed for repairing tarsal plate defects, thereby offering an alternative therapeutic approach for treating posterior lamellar defects in clinic settings.
Objective: To compare the effectiveness of tranexamic acid (TXA) in reducing blood loss and decreasing surgery duration in craniomaxillofacial surgery. Methods: The literature was searched systematically for all comparative studies of the effect of TXA on craniomaxillofacial surgery with placebo to evaluate the efficacy of TXA in craniomaxillofacial surgery. The primary outcome was intraoperative blood loss, and secondary outcomes were postoperative hematocrit, postoperative hemoglobin, and operation duration. Results: This systematic review included 16 studies consisting of 958 patients. Meta-analysis revealed that compared with the placebo group, the TXA group showed a significant reduction in intraoperative blood loss of 139.81 mL (95% confidence interval, CI: −179.66 to −99.96 mL; p < 0.01), a shortening of the maxillary surgery duration of 15.48 min (95% CI: −21.03 to −9.92 min; p < 0.01), an elevation of the postoperative hemoglobin level of 0.74 mg/dL (95% CI: 0.42 to 1.07 mg/dL; p < 0.01), and a limited effect on increasing the postoperative hematocrit level of 1.77% (95% CI: 0.17 to 3.36; p = 0.03). Conclusion: The use of TXA in craniomaxillofacial surgery can effectively reduce intraoperative blood loss, maintain elevate postoperative hemoglobin and hematocrit levels, and reduce the operation duration.
Balanced local pH serves a vital role in extracellular microenvironment homeostasis. However, the impact of local pH disturbance on the proliferation, differentiation, and bone formation potential of human adipose-derived stem cells (ASCs) remain to be fully addressed. In the present study, we evaluated proliferation and multilineage differentiation ability in vitro by culturing human ASCs in mediums at pH 6.8 (acidic medium) and 7.4 (normal medium). The results indicated that the proliferation was markedly inhibited after 120 hours of culture in an acidic medium (p < 0.05). Additionally, osteogenic differentiation ability was also hampered by the acidic condition. Notably, adipogenic capacity was unaffected. ASCs were then seeded in Ultrafoam constructs and induced into chondrocytes and hypertrophic chondrocytes in vitro to verify the chondrogenic ability in acidic and normal medium. The normal condition group presented glycosaminoglycan (GAG) accumulation and large chondrocyte-shaped cells found in lacunae. In contrast, the acidic medium group showed no typical chondrocytes or GAG. When implanted subcutaneously in mice, there was no de novo bone tissue in the acidic cultured constructs when compared to the bone formation and blood vessel invasion of the normal pH group, which was consistent with the in vitro study. In conclusion, even minor changes in extracellular pH could significantly affect the proliferation and differentiation ability of ASCs. Thus, the control of extracellular pH condition is crucially important to successful chondrogenic priming, tissue engineering, and the study of chondrocyte physiology and functions. (Am J Transl Med 2020. 5(1):25-36).
Reconstruction of eyelid defects, especially the posterior lamella, remains challenging because of its anatomical complexity, functional considerations, and aesthetic concerns. The goals of eyelid reconstruction include restoring eyelid structure and function and achieving an aesthetically acceptable appearance. An in-depth understanding of the complex eyelid anatomy and several reconstructive principles are mandatory to achieve these goals. Currently, there are multiple surgical treatment options for eyelid reconstruction, including different flaps, grafts, and combinations of them. This comprehensive review outlines the principles of reconstruction and discusses the indications, advantages, and disadvantages of currently available surgical techniques. We also propose our clinical thinking for solving specific clinical questions in eyelid reconstruction and offer perspectives on new potential methodologies in the future.
Diabetes presents a pressing healthcare crisis, necessitating innovative solutions. Organoid technologies have rapidly advanced, leading to the emergence of bioengineering islet organoids as an unlimited source of insulin-producing cells for treating insulin-dependent diabetes. This advancement surpasses the need for cadaveric islet transplantation. However, clinical translation of this approach faces two major limitations: immature endocrine function and the absence of a perfusable vasculature compared to primary human islets. In this review, we summarize the latest developments in bioengineering functional islet organoids in vitro and promoting vascularization of organoid grafts before and after transplantation. We highlight the crucial roles of the vasculature in ensuring long-term survival, maturation, and functionality of islet organoids. Additionally, we discuss key considerations that must be addressed before clinical translation of islet organoid-based therapy, including functional immaturity, undesired heterogeneity, and potential tumorigenic risks.
Reconstruction of posterior lamellar eyelids remains challenging due to their delicate structure, highly specialized function, and cosmetic concerns. Current clinically available techniques for posterior lamellar reconstruction mainly focus on reconstructing the contour of the eyelids. However, the posterior lamella not only provides structural support for the eyelid but also offers a smooth mucosal surface to facilitate globe movement and secrete lipids to maintain ocular surface homeostasis. Bioengineered posterior lamellar substitutes developed via acellular or cellular approaches have shown promise as alternatives to current therapies and encouraging outcomes in animal studies and clinical conditions. Here, we provide a brief reference on the current application of autografts, biomaterials, and tissue-engineered substitutes for posterior lamellar eyelid reconstruction. We also shed light on future challenges and directions for eyelid regeneration strategies and offer perspectives on transitioning replacement strategies to regeneration strategies for eyelid reconstruction in the future.
Traditional bone tissue engineering (BTE) strategies induce direct bone-like matrix formation by mimicking the embryological process of intramembranous ossification. However, the clinical translation of these clinical strategies for bone repair is hampered by limited vascularization and poor bone regeneration after implantation in vivo. An alternative strategy for overcoming these drawbacks is engineering cartilaginous constructs by recapitulating the embryonic processes of endochondral ossification (ECO); these constructs have shown a unique ability to survive under hypoxic conditions as well as induce neovascularization and ossification. Such developmentally engineered constructs can act as transient biomimetic templates to facilitate bone regeneration in critical-sized defects. This review introduces the concept and mechanism of developmental BTE, explores the routes of endochondral bone graft engineering, highlights the current state of the art in large bone defect reconstruction via ECO-based strategies, and offers perspectives on the challenges and future directions of translating current knowledge from the bench to the bedside.
Objective The classic chondrocyte isolation protocol is a 1-step enzymatic digestion protocol in which cartilage samples are digested in collagenase solution for a single, long period. However, this method usually results in incomplete cartilage dissociation and low chondrocyte quality. In this study, we aimed to develop a rapid, high-efficiency, and flexible chondrocyte isolation protocol for cartilage tissue engineering. Design Cartilage tissues harvested from rabbit ear, rib, septum, and articulation were minced and subjected to enzymatic digestion using the classic protocol or the newly developed sequential protocol. In the classic protocol, cartilage fragments were subjected to one 12-hour digestion. In the sequential protocol, cartilage fragments were sequentially subjected to 2-hour first digestion, followed by two 3-hour digestions. The collected cells were then subjected to analyses of cell-yield efficiency, viability, proliferation, phenotype, and cartilage matrix synthesis capacity Results Overall, the sequential protocol exhibited higher cell-yield efficiency than the classic protocol for the 4 cartilage types. The cells harvested from the second and third digestions demonstrated higher cell viability, more proliferative activity, a better chondrocyte phenotype, and a higher cartilage-specific matrix synthesis ability than those harvested from the first digestion and after the classic 1-step protocol. Conclusions The sequential protocol is a rapid, flexible, high-efficiency chondrocyte isolation protocol for different cartilage tissues. We recommend using this protocol for chondrocyte isolation, and in particular, the cells obtained after the subsequent 3-hour sequential digestions should be used for chondrocyte-based therapy.
Keloids are benign fibroproliferative tumors that display many cancer-like characteristics, such as progressive uncontrolled growth, lack of spontaneous regression, and extremely high rates of recurrence. Polo-like kinase 4 (PLK4) was recently identified as a master regulator of centriole replication, and its aberrant expression is closely associated with tumorigenesis. This study aimed to investigate the expression and biological role of PLK4 in the pathogenesis of keloids.We evaluated the expression of PLK4 in keloids and adjacent normal skin tissue samples. Then, we established PLK4 knockdown and overexpression cell lines in keloid fibroblasts (KFs) and normal skin fibroblasts (NFs), respectively, to investigate the roles of PLK4 in the regulation of proliferation, migration, invasion, apoptosis, and cell cycle in KFs. Centrinone B (Cen-B), a highly selective PLK4 inhibitor, was used to inhibit PLK4 activity in KFs to evaluate the therapeutic effect on KFs.We discovered that PLK4 was overexpressed in keloid dermal samples and KFs compared with adjacent normal skin samples and NFs derived from the same patients. High PLK4 expression was positively associated with the proliferation, migration, and invasion of KFs. Furthermore, knockdown of PLK4 expression or inhibition of PLK4 activity by Cen-B suppressed KF growth, induced KF apoptosis via the caspase-9/3 pathway, and induced cell cycle arrest at the G0/G1 phase in vitro.These findings demonstrate that PLK4 is a critical regulator of KF proliferation, migration, and invasion, and thus, Cen-B is a promising candidate drug for keloid treatment.
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