Po-Ling Kuo

Promoting self‐organized regeneration, rather than nonfunctional repair, has emerged as a leading strategy for treating soft tissue injuries. Tissue self‐organization typically occurs in scaffold‐free environments; however, scaffolds can offer long‐range support, which is often essential for healing extensive injuries. In this study, we develop a balanced therapeutic strategy to facilitate the regeneration of completely ruptured Achilles tendons. Scaffold‐free mimetic effects, including surface modifications and the creation of fiber‐free void spaces at three scales ranging from 100 μm to several millimeters, are integrated into microfibrous polycaprolactone scaffolds. Modifications to scaffold architecture and surgical techniques are also developed to facilitate the tissue‐assisted dynamic removal of scaffolds from the injury site. We show that these modifications reduce immune infiltration, improve the alignment of regenerated tendon fibers, and enhance the restoration of gait patterns through a synergistic effect between the scaffolds and the regenerating tissue. Our findings highlight the potential of creating scaffold‐free mimetic environments within scaffolds to promote soft tissue regeneration.

The crimped appearance of native collagen fibrils in youthful tissues serves as a mechanical buffer and phenotype determinant for resident cells. In vitro platforms emulating these native crimped networks facilitate the study of cell-matrix dynamics in various pathophysiological contexts. However, creating fibrillar networks with sizes and crimping matching native tissues using collagen-derived substrates remains challenging. We present an innovative approach to produce spontaneous, tunable crimping of electrospun, aligned gelatin methacryloyl nanofibrils using limited hydration. The diameter of the synthesized fibrils approximated that of native fibrils. Beyond individual fibril crimping, the network exhibited large-scale, periodic crimping with wavelengths matching native collagen networks. Tensile stress tests revealed that crimping reduced network stiffness but enhanced stretchability, consistent with native tissues. Additionally, crimping promoted cell translocation into the network. Fibroblasts cultured on crimped fibrils showed smaller cell areas, higher vinculin and α-tubulin expression, and lower α-smooth muscle actin levels compared to those on straight fibrils. This novel method not only replicates the native fibril characteristics using collagen-derived materials, but also offers a valuable tool for advancing our understanding of cell-matrix interactions, with significant implications for tissue engineering and regenerative medicine.

Ultrasound imaging has emerged as a valuable tool in the diagnosis and management of peripheral nerve disorders. The integration of deep learning with ultrasound technology has shown remarkable potential in enhancing diagnostic accuracy and efficiency. This review focuses on the application of deep learning-based approaches in ultrasound diagnostics for peripheral nerve diseases, with particular emphasis on median nerve segmentation in carpal tunnel syndrome. Structured to provide a clear and thorough understanding of the current landscape and future directions, the paper is organized into several key sections: (1) an overview of the current state of the field, (2) research objectives and notable achievements, (3) challenges in dataset utilization specific to medical imaging, (4) trends in the development of deep learning models tailored for ultrasound analysis, and (5) potential future directions for research and clinical application. This review seeks to bridge the gap between technological advancements and clinical practice, potentially paving the way for more accurate and efficient diagnosis and treatment in the field of peripheral nerve disorders.

There is an emerging trend to employ dynamic sonography in the diagnosis of entrapment neuropathy, which exhibits aberrant spatiotemporal characteristics of the entrapped nerve when adjacent tissues move. However, the manual tracking of the entrapped nerve in consecutive images demands tons of human labors and impedes its popularity clinically. Here we evaluated the performance of automated median nerve segmentation in dynamic sonography using a variety of deep learning models pretrained with ImageNet, including DeepLabV3+, U-Net, FPN, and Mask-R-CNN. Dynamic ultrasound images of the median nerve at across wrist level were acquired from 52 subjects diagnosed as carpal tunnel syndrome when they moved their fingers. The videos of 16 subjects exhibiting diverse appearance and that of the remaining 36 subjects were used for model test and training, respectively. The centroid, circularity, perimeter, and cross section area of the median nerve in individual frame were automatically determined from the inferred nerve. The model performance was evaluated by the score of intersection over union (IoU) between the annotated and model-predicted data. We found that both DeepLabV3+ and Mask R-CNN predicted median nerve the best with averaged IOU scores close to 0.83, which indicates the feasibility of automated median nerve segmentation in dynamic sonography using deep learning.

This study aimed to investigate the effect of different injectate volumes on ultrasonographic parameters and the correlation to clinical outcomes under perineural dextrose injection (PDI). In this post hoc analysis of the randomized, double-blinded, three-arm trial, ultrasound-guided PDI with either 1 mL, 2 mL, and 4 mL 5% dextrose water was administered, respectively, in 14, 14, and 17 patients. Ultrasound outcomes included mobility, shear-wave elastography (SWE), and cross-sectional area (CSA) of the median nerve; clinical outcomes were Visual Analog Scale (VAS) and Boston Carpal Tunnel Questionnaire (BCTQ) score. Outcomes were measured before injection, and after injection at the 1st, 4th, 12th, and 24th week. For ultrasound outcomes, CSA decreased significantly from baseline data at all follow-up time-points in the 2 mL group (p = 0.005) and the 4 mL group (p = 0.015). The mean change of mobility from baseline showed a greater improvement on the 4 mL group than the other groups at the 1st week post-injection. For clinical outcomes, negative correlation between the VAS and mobility at the 1st (p = 0.046) and 4th week (p = 0.031) post-injection in the 4 mL group were observed. In conclusion, PDI with higher volume yielded better nerve mobility and decreased CSA of median nerve, but no changes of nerve elasticity.

Entrapment neuropathy (EN) is a prevalent and debilitative condition caused by a complex pathogenesis that involves a chronic compression–edema–ischemia cascade and perineural adhesion that results in excessive shear stress during motion. Despite decades of research, an easily accessible and surgery-free animal model mimicking the mixed etiology is currently lacking, thus limiting our understanding of the disease and the development of effective therapies. In this proof-of-concept study, we used ultrasound-guided perineural injection of a methoxy poly(ethylene glycol)-b-Poly(lactide-co-glycoilide) carboxylic acid (mPEG-PLGA-BOX) hydrogel near the rat’s sciatic nerve to induce EN, as confirmed sonographically, electrophysiologically, and histologically. The nerve that was injected with hydrogel appeared unevenly contoured and swollen proximally with slowed nerve conduction velocities across the injected segments, thus showing the compressive features of EN. Histology showed perineural cellular infiltration, deposition of irregular collagen fibers, and a possible early demyelination process, thus indicating the existence of adhesions. The novel method provides a surgery-free and cost-effective way to establish a small-animal model of EN that has mixed compression and adhesion features, thus facilitating the additional elucidation of the pathophysiology of EN and the search for promising treatments.

Tumor antigen-specific cytotoxic T lymphocyte (CTL) is a promising agent for cancer therapy. Most solid tumors are characterized by increased interstitial fluid pressure (IFP) and dense collagen capsule, which form physical barriers to impede cancer treatment. However, it remains unclear how CTL-mediated anticancer response is affected at the presence of these obstacles. Using a microfluidic-based platform mimicking these obstacles, we investigated the migration characteristics and performance of anticancer response of CTLs targeting hepatic cancer cells via antigen-specific and allogeneic recognition. The device consisted of slit channels mimicking the narrow interstitial paths constrained by the fibrous capsule and increased IFP was simulated by applying hydrostatic pressure to the tumor center. We found that antigen-specificity of CTLs against the targeted cancer cells determined the cytotoxic efficacy of the CTLs but did not significantly affect the success rate in CTLs that attempted to infiltrate into the tumor center. When increased IFP was present in the tumor center, CTL recruitment to tumor peripheries was promoted but success of infiltration was hindered. Our results highlight the importance of incorporating the physical characteristics of tumor interstitum into the development of CTL-based cancer immunotherapy.

Ultrasound-guided injection is a widely used technique, however, it takes substantial amounts of time for novices to master the skill. The most critical issue to improve the accuracy of the injection is to align the needle with the scan plane of the ultrasound beam and orient the needle angle after piercing skin to aim at the targeted tissue. In the present study, we developed a two-dimensional laser align device to assist physicians to accurately position the needle in the scan plane and advance it at an angle correctly pointing to the target. The device is inexpensive, light-weighted, and easy to fabricate and accommodate for any types of ultrasound probe. Statistical analysis revealed that the assistance with our device significantly reduced the successful targeting time and times of retargeting in comparison with the traditional freehand approach or only with in-plane assistance for inexperience subjects. Our results indicate that the device exhibits great potential in effectively reducing the learning time to master the skill and speeding up the procedure for ultrasound-guided injection.