skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: The Autonomization Principle in Vascularized Flaps: An Alternative Strategy for Composite Tissue Scaffold In Vivo Revascularization
Autonomization is a physiological process allowing a flap to develop neo-vascularization from the reconstructed wound bed. This phenomenon has been used since the early application of flap surgeries but still remains poorly understood. Reconstructive strategies have greatly evolved since, and fasciocutaneous flaps have progressively replaced muscle-based reconstructions, ensuring better functional outcomes with great reliability. However, plastic surgeons still encounter challenges in complex cases where conventional flap reconstruction reaches its limitations. Furthermore, emerging bioengineering applications, such as decellularized scaffolds allowing a complex extracellular matrix to be repopulated with autologous cells, also face the complexity of revascularization. The objective of this article is to gather evidence of autonomization phenomena. A systematic review of flap autonomization is then performed to document the minimum delay allowing this process. Finally, past and potential applications in bio- and tissue-engineering approaches are discussed, highlighting the potential for in vivo revascularization of acellular scaffolds.  more » « less
Award ID(s):
1941543
PAR ID:
10637005
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ;
Publisher / Repository:
MDPI
Date Published:
Journal Name:
Bioengineering
Volume:
10
Issue:
12
ISSN:
2306-5354
Page Range / eLocation ID:
1440
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Abstract Three-dimensional (3D) bioprinting is a promising technique for creating patient-specific 3D scaffolds of tissues or organs. An appropriate culturing process is critical to confirm encapsulated and seeded cells’ excellent viability and proliferation into scaffolds materials. Traditional stagnant cell culturing methods don’t ensure entering medium inside areas or passing through the scaffolds. To resolve this issue, we developed a customized perfusion bioreactor to supply the growth medium dynamically to the encapsulated or seeded cells. Our custom-designed bioreactor improves the in vivo stimuli and conditions, which may enhance cell viability and proliferation performance. A design of a dual medium tank was utilized allowing the replacement of already-used medium without interrupting perfusion. Accommodating an array of cassettes in a newly designed perfusion chamber allowed a wide range of scaffolds with various size and shapers to hold. In this paper, we explored fluid flow response on scaffolds fabricated with various material compositions with different viscosities. We fabricated scaffolds following a 00–900 deposition pattern with 8% Alginate, 4% Alginate-4% Carboxymethyl Cellulose (CMC), and 2% Alginate-6% CMC incubated, allowing a constant fluid flow for various periods such as 1, 2, 4, and 8 hours. The change of scaffolds fabricated with multiple material compositions was determined in terms of swelling rate, i.e., change of filament width, and material diffusion, i.e., comparison of dry material weight before and after incubation. This comparative study can assist in application-based materials selection suitable for incubating in a perfusion bioreactor. 
    more » « less
  2. Machine perfusion has developed rapidly since its first use in solid organ transplantation. Likewise, reconstructive surgery has kept pace, and ex vivo perfusion appears as a new trend in vascularized composite allotransplants preservation. In autologous reconstruction, fasciocutaneous flaps are now the gold standard due to their low morbidity (muscle sparing) and favorable functional and cosmetic results. However, failures still occasionally arise due to difficulties encountered with the vessels during free flap transfer. The development of machine perfusion procedures would make it possible to temporarily substitute or even avoid microsurgical anastomoses in certain complex cases. We performed oxygenated acellular sub-normothermic perfusions of fasciocutaneous flaps for 24 and 48 h in a porcine model and compared continuous and intermittent perfusion regimens. The monitored metrics included vascular resistance, edema, arteriovenous oxygen gas differentials, and metabolic parameters. A final histological assessment was performed. Porcine flaps which underwent successful oxygenated perfusion showed minimal or no signs of cell necrosis at the end of the perfusion. Intermittent perfusion allowed overall better results to be obtained at 24 h and extended perfusion duration. This work provides a strong foundation for further research and could lead to new and reliable reconstructive techniques. 
    more » « less
  3. Objectives:Blood perfusion quality of a flap is the main prognostic factor for success. Microvascular evaluation remains mostly inaccessible. We aimed to evaluate the microflow imaging mode, MV-Flow, in assessing flap microvascularization in a pig model of the fascio-cutaneous flap. Methods:On five pigs, bilateral saphenous fascio-cutaneous flaps were procured on the superficial femoral vessels. A conventional ultrasound evaluation in pulsed Doppler and color Doppler was conducted on the ten flaps allowing for the calculation of the saphenous artery flow rate. The MV-Flow mode was then applied: for qualitative analysis, with identification of saphenous artery collaterals; then quantitative, with repeated measurements of the Vascularity Index (VI), percentage of pixels where flow is detected relative to the total ultrasound view area. The measurements were then repeated after increasing arterial flow by clamping the distal femoral artery. Results:The MV-Flow mode allowed a better follow-up of the saphenous artery’s collaterals and detected microflows not seen with the color Doppler. The VI was correlated to the saphenous artery flow rate (Spearman rho of 0.64;p= 0.002) and allowed to monitor the flap perfusion variations. Conclusion:Ultrasound imaging of microvascularization by MV-Flow mode and its quantification by VI provides valuable information in evaluating the microvascularization of flaps. 
    more » « less
  4. It is becoming increasingly popular for distributed systems to exploit offload to reduce load on the CPU. Remote Direct Memory Access (RDMA) offload, in particular, has become popular. However, RDMA still requires CPU intervention for complex offloads that go beyond simple remote memory access. As such, the offload potential is limited and RDMA-based systems usually have to work around such limitations. We present RedN, a principled, practical approach to implementing complex RDMA offloads, without requiring any hardware modifications. Using self-modifying RDMA chains, we lift the existing RDMA verbs interface to a Turing complete set of programming abstractions. We explore what is possible in terms of offload complexity and performance with a commodity RDMA NIC. We show how to integrate these RDMA chains into applications, such as the Memcached key-value store, allowing us to offload complex tasks such as key lookups. RedN can reduce the latency of key-value get operations by up to 2.6× compared to state-of-the-art KV designs that use one-sided RDMA primitives (e.g., FaRM-KV), as well as traditional RPC-over-RDMA approaches. Moreover, compared to these baselines, RedN provides performance isolation and, in the presence of contention, can reduce latency by up to 35× while providing applications with failure resiliency to OS and process crashes. 
    more » « less
  5. Abstract Although still in its early stages, the production and investigation of 3D magnetic nanostructures signify a major advancement in both fundamental research and practical applications, with immense potential for next‐generation technologies. Here, for the fabrication of the 3D nanostructures, an innovative approach selecting aS= 1/2 4,4′‐dicyano‐2,2′‐biphenylene‐fused tetrazolinyl radical is adopted, chemically stable and thermodynamically robust, allowing thin film processing and growth. Interdigitated gold‐silicon dioxide hybrid surfaces are used as substrates since gold and silicon dioxide are two technologically relevant materials. The ability to: (1) grow radical nanostructures are demonstrated that retain their magnetic properties, (2) adjust their morphology and size, (3) selectively remove nanostructures from specific substrate regions using distilled water, and (4) return substrates to their pristine condition, making them reusable after washing. This research not only aims to produce innovative 3D nanostructures but also strives to improve efficiency and minimize consumption, aligning with the principles of circular economy. This approach is particularly beneficial for expensive materials, such as gold, or patterned hybrid substrates that require complex fabrication techniques. 
    more » « less