Three-dimensional meltblowing as a high-speed fabrication process for tendon tissue engineered scaffolds

Bioprinting · 2025-04-01 · 4 citations

Rotator cuff tears continue to be a critical challenge for successful repair due to the formation of fibrotic scar tissue during healing. Tendon tissue engineering seeks to improve these outcomes using nonwoven fabrication methods to produce biomimetic scaffolds. Meltblowing has several advantages over other nonwoven approaches including non-toxic fabrication processes and being high-throughput and economical, while accurately producing fiber diameters comparable to native tendon microstructure. Recently 3D meltblowing (3DMB) introduced high degrees of tunability to the core process, allowing for production of highly aligned fiber mats at anatomically relevant dimensions. Here, we evaluated 3DMB scaffolds fabricated using poly-L-lactic acid (PLA) and poly-ε-caprolactone (PCL) by characterizing scaffold properties before and after culture with human adipose stem cells (hASCs). Mechanical and fiber characterization of 3DMB scaffolds closely resembled tendon microarchitecture by exhibiting high fiber alignment and mechanical anisotropy. hASC-seeded 3DMB scaffolds after 28 days of culture proliferated and deposited aligned tendon-like extracellular matrix. Furthermore, cell culture enhanced the Young's modulus of PLA 3DMB scaffolds and improved yield stress, yield stretch, and stiffness of both 3DMB scaffolds. The proteome of cultured 3DMB scaffolds increased expression of tendon-related proteins after 28 days of culture, but polymer-dependent differences in glycoprotein composition was observed. Together, 3DMB is a promising method for tendon tissue engineering, by showing improved fiber and mechanical properties compared to meltblown scaffolds. However, while an improvement on prior iterations, continued development of this 3DMB technology is needed to better mimic the mechanical properties and biologic composition of native tendon. • Current scaffold fabrication methods for tendon tissue engineering face challenges in large-scale manufacturing. • Meltblowing is a nonwoven fabrication process used in various commercial products. • This process can also create scaffolds with tunable fiber and mechanical properties that resemble those found in tendons. • Scaffolds cultured with adipose stem cells developed tendon-like matrix. • Further research into these scaffolds may lead to scalable options for tissue engineering applications.

Application of Tendon‐Derived Matrix and Carbodiimide Crosslinking Matures the Engineered Tendon‐Like Proteome on Meltblown Scaffolds

Journal of Tissue Engineering and Regenerative Medicine · 2025-01-01 · 1 citations

Background: Tendon injuries are increasingly common and heal by fibrosis rather than scar‐less regeneration. Tissue engineering seeks to improve repair using synthetic polymer scaffolds with biomimetic factors to enhance the regenerative potential. Methods: In this study, we compared three groups, namely, poly(lactic acid) (PLA) meltblown scaffolds, PLA meltblown scaffolds coated with tendon‐derived matrix (TDM), and PLA meltblown scaffolds with carbodiimide crosslinked TDM (2.5:1:1 EDC:NHS:COOH ratio) (EDC‐TDM) and determined their potential for engineered tendon development. We cultured human adipose stem cells (hASCs) for 28 days on meltblown scaffolds ( n = 4–6/group) and measured tensile mechanical function, matrix synthesis, and matrix composition using biochemical assays and proteomics. Results: Coating PLA meltblown scaffolds with TDM improved yield stretch and stress at 28 days compared with PLA. Matrix synthesis rates for TDM or EDC‐TDM were similar to PLA. Proteomic analysis revealed that hASCs produced a collagen‐rich extracellular matrix, with many tendon‐related matrix proteins. Coating scaffolds with TDM led to an increase in collagen type I whereas EDC‐TDM scaffolds had an increase in glycoproteins and ECM regulators compared with other groups, consistent with increased maturity of the newly deposited matrix. Conclusions: TDM coating and crosslinking of meltblown scaffolds demonstrated matricellular benefits for the proteome of engineered tendon development but provided fewer clear benefits toward mechanical, biochemical, and rate of matrix accumulation than expected, and that previous work with electrospun scaffolds would suggest. However, electrospun scaffolds have different fiber structure and microarchitecture than meltblown, suggesting that further consideration of these differences and refinement of TDM application methods to meltblown scaffolds is required.

Impact of polymer degradation on cellular behavior in tissue engineering

Bioprinting · 2025-07-30 · 3 citations

Tissue engineering frequently employs biomimetic scaffolds to direct cell responses and facilitate the differentiation of cells into specific lineages. Biodegradable scaffolds mitigate immune responses, stress shielding concerns in load bearing tissues, and the need for secondary or revision surgical procedures for retrieval. However, during the degradation process, scaffold properties such as fiber diameter, fiber porosity, fiber alignment, surface properties and mechanical properties undergo changes that significantly alter the initial properties. This review aims to comprehensively assess the impact of degradation on scaffold properties from the perspective of their effects on cellular behavior by addressing four key aspects of polymer degradation: First, we review the variables that influence scaffold degradation. Second, we examine how degradation impacts scaffold properties. Third, we explore the effects of scaffold degradation products. Finally, we investigate measures to increase tunability of degradation rate. Harnessing and incorporating these degradation mechanisms into scaffold design holds great promise for advancing the development of tissue-engineered scaffolds, ultimately improving their efficacy and clinical utility.

Aging and obesity prime the methylome and transcriptome of adipose stem cells for disease and dysfunction

UNC Libraries · 2025-07-26

The epigenome of stem cells occupies a critical interface between genes and environment, serving to regulate expression through modification by intrinsic and extrinsic factors. We hypothesized that aging and obesity, which represent major risk factors for a variety of diseases, synergistically modify the epigenome of adult adipose stem cells (ASCs). Using integrated RNA- and targeted bisulfite-sequencing in murine ASCs from lean and obese mice at 5- and 12-months of age, we identified global DNA hypomethylation with either aging or obesity, and a synergistic effect of aging combined with obesity. The transcriptome of ASCs in lean mice was relatively stable to the effects of age, but this was not true in obese mice. Functional pathway analyses identified a subset of genes with critical roles in progenitors and in diseases of obesity and aging. Specifically, Mapt, Nr3c2, App, and Ctnnb1 emerged as potential hypomethylated upstream regulators in both aging and obesity (AL vs. YL and AO vs. YO), and App, Ctnnb1, Hipk2, Id2, and Tp53 exhibited additional effects of aging in obese animals. Furthermore, Foxo3 and Ccnd1 were potential hypermethylated upstream regulators of healthy aging (AL vs. YL), and of the effects of obesity in young animals (YO vs. YL), suggesting that these factors could play a role in accelerated aging with obesity. Finally, we identified candidate driver genes that appeared recurrently in all analyses and comparisons undertaken. Further mechanistic studies are needed to validate the roles of these genes capable of priming ASCs for dysfunction in aging- and obesity-associated pathologies.

The development of a collagen-nanoscale hydroxyapatite three-dimensional (3D) in vitro culture system for reproducing osteocyte differentiation and tissue mineralization

Biomaterials · 2025-06-09 · 3 citations

Preclinical tendon and ligament models: Beyond the 3Rs (replacement, reduction, and refinement) to 5W1H (why, who, what, where, when, how)

Journal of Orthopaedic Research® · 2023-08-13 · 35 citations

Several tendon and ligament animal models were presented at the 2022 Orthopaedic Research Society Tendon Section Conference held at the University of Pennsylvania, May 5 to 7, 2022. A key objective of the breakout sessions at this meeting was to develop guidelines for the field, including for preclinical tendon and ligament animal models. This review summarizes the perspectives of experts for eight surgical small and large animal models of rotator cuff tear, flexor tendon transection, anterior cruciate ligament tear, and Achilles tendon injury using the framework: "Why, Who, What, Where, When, and How" (5W1H). A notable conclusion is that the perfect tendon model does not exist; there is no single gold standard animal model that represents the totality of tendon and ligament disease. Each model has advantages and disadvantages and should be carefully considered in light of the specific research question. There are also circumstances when an animal model is not the best approach. The wide variety of tendon and ligament pathologies necessitates choices between small and large animal models, different anatomic sites, and a range of factors associated with each model during the planning phase. Attendees agreed on some guiding principles including: providing clear justification for the model selected, providing animal model details at publication, encouraging sharing of protocols and expertise, improving training of research personnel, and considering greater collaboration with veterinarians. A clear path for translating from animal models to clinical practice was also considered as a critical next step for accelerating progress in the tendon and ligament field.

Aging and obesity prime the methylome and transcriptome of adipose stem cells for disease and dysfunction

The FASEB Journal · 2023-02-16 · 6 citations

The epigenome of stem cells occupies a critical interface between genes and environment, serving to regulate expression through modification by intrinsic and extrinsic factors. We hypothesized that aging and obesity, which represent major risk factors for a variety of diseases, synergistically modify the epigenome of adult adipose stem cells (ASCs). Using integrated RNA- and targeted bisulfite-sequencing in murine ASCs from lean and obese mice at 5- and 12-months of age, we identified global DNA hypomethylation with either aging or obesity, and a synergistic effect of aging combined with obesity. The transcriptome of ASCs in lean mice was relatively stable to the effects of age, but this was not true in obese mice. Functional pathway analyses identified a subset of genes with critical roles in progenitors and in diseases of obesity and aging. Specifically, Mapt, Nr3c2, App, and Ctnnb1 emerged as potential hypomethylated upstream regulators in both aging and obesity (AL vs. YL and AO vs. YO), and App, Ctnnb1, Hipk2, Id2, and Tp53 exhibited additional effects of aging in obese animals. Furthermore, Foxo3 and Ccnd1 were potential hypermethylated upstream regulators of healthy aging (AL vs. YL), and of the effects of obesity in young animals (YO vs. YL), suggesting that these factors could play a role in accelerated aging with obesity. Finally, we identified candidate driver genes that appeared recurrently in all analyses and comparisons undertaken. Further mechanistic studies are needed to validate the roles of these genes capable of priming ASCs for dysfunction in aging- and obesity-associated pathologies.

Tendon‐derived matrix crosslinking techniques for electrospun multi‐layered scaffolds

Journal of Biomedical Materials Research Part A · 2023-07-25 · 2 citations

Abstract Tendon tears are common and healing often occurs incompletely and by fibrosis. Tissue engineering seeks to improve repair, and one approach under investigation uses cell‐seeded scaffolds containing biomimetic factors. Retention of biomimetic factors on the scaffolds is likely critical to maximize their benefit, while minimizing the risk of adverse effects, and without losing the beneficial effects of the biomimetic factors. The aim of the current study was to evaluate cross‐linking methods to enhance the retention of tendon‐derived matrix (TDM) on electrospun poly(ε‐caprolactone) (PCL) scaffolds. We tested the effects of ultraviolet (UV) or carbodiimide (EDC:NHS:COOH) crosslinking methods to better retain TDM to the scaffolds and stimulate tendon‐like matrix synthesis. Initially, we tested various crosslinking configurations of carbodiimide (2.5:1:1, 5:2:1, and 10:4:1 EDC:NHS:COOH ratios) and UV (30 s 1 J/cm 2 , 60 s 1 J/cm 2 , and 60 s 4 J/cm 2 ) on PCL films compared to un‐crosslinked TDM. We found that no crosslinking tested retained more TDM than coating alone (Kruskal‐Wallis: p > .05), but that human adipose stem cells (hASCs) spread most on the 60 s 1 J/cm 2 UV‐ and 2.5:1:1 EDC‐crosslinked films (Kruskal‐Wallis: p < .05). Next, we compared the effects of 60 s 1 J/cm 2 UV‐ and 2.5:1:1 EDC‐crosslinked to TDM‐coated and untreated PCL scaffolds on hASC‐induced tendon‐like differentiation. UV‐crosslinked scaffolds had greater modulus and stiffness than PCL or TDM scaffolds, and hASCs spread more on UV‐crosslinked scaffolds (ANOVA: p < .05). Fourier transform infrared spectra revealed that UV‐ or EDC‐crosslinking TDM did not affect the peaks at wavenumbers characteristic of tendon. Crosslinking TDM to electrospun scaffolds improves tendon‐like matrix synthesis, providing a viable strategy for improving retention of TDM on electrospun PCL scaffolds.

Research perspectives—Pipelines to human tendon transcriptomics

Journal of Orthopaedic Research® · 2022-03-03 · 7 citations

Tendon transcriptomics is a rapidly growing field in musculoskeletal biology. The ultimate aim of many current tendon transcriptomic studies is characterization of in vitro, ex vivo, or in vivo, healthy, and diseased tendon microenvironments to identify the underlying pathways driving human tendon pathology. The transcriptome interfaces between genomic, proteomic, and metabolomic signatures of the tendon cellular niche and the response of this niche to stimuli. Some of the greatest bottlenecks in tendon transcriptomics relate to the availability and quality of human tendon tissue, hence animal tissues are frequently used even though human tissue is most translationally relevant. Here, we review the variability associated with human donor and procurement factors, such as whether the tendon is cadaveric or a clinical remnant, and how these variables affect the quality and relevance of the transcriptomes obtained. Moreover, age, sex, and health demographic variables impact the human tendon transcriptome. Tendons present tissue-specific challenges for cell, nuclei, and RNA extraction that include a dense extracellular matrix, low cellularity, and therefore low RNA yield of variable quality. Consideration of these factors is particularly important for single-cell and single-nuclei resolution transcriptomics due to the necessity for unbiased and representative cell or nuclei populations. Different cell, nuclei, and RNA extraction methods, library preparation, and quality control methods are used by the tendon research community and attention should be paid to these when designing and reporting studies. We discuss the different components and challenges of human tendon transcriptomics, and propose pipelines, quality control, and reporting guidelines for future work in the field.

The association between anterior shoulder joint capsule thickening and glenoid deformity in primary glenohumeral osteoarthritis

Journal of Shoulder and Elbow Surgery · 2022-03-21 · 11 citations