Bio-Medical Materials and Engineering - Volume 32, issue 3

Authors: Funai, Takashi | Kataoka, Hiroyuki | Yokota, Hideo | Suzuki, Taka-aki

Article Type: Research Article

Abstract: BACKGROUND: Mechanical simulations for biological tissues are effective technology for development of medical equipment, because it can be used to evaluate mechanical influences on the tissues. For such simulations, mechanical properties of biological tissues are required. For most biological soft tissues, stress tends to increase monotonically as strain increases. OBJECTIVE: Proposal of a strain-energy function that can guarantee monotonically increasing trend of biological soft tissue stress-strain relationships and applicability confirmation of the proposed function for biological soft tissues. METHOD: Based on convexity of invariants, a polyconvex strain-energy function that can reproduce monotonically increasing trend was derived. …In addition, to confirm its applicability, curve-fitting of the function to stress-strain relationships of several biological soft tissues was performed. RESULTS: A function depending on the first invariant alone was derived. The derived function does not provide such inappropriate negative stress in the tensile region provided by several conventional strain-energy functions. CONCLUSIONS: The derived function can reproduce the monotonically increasing trend and is proposed as an appropriate function for biological soft tissues. In addition, as is well-known for functions depending the first invariant alone, uniaxial-compression and equibiaxial-tension of several biological soft tissues can be approximated by curve-fitting to uniaxial-tension alone using the proposed function. Show more

Keywords: Biological tissue, biomechanical simulation, finite element method, hyperelasticity, tissue modelling

DOI: 10.3233/BME-196015

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 3, pp. 131-144, 2021

Authors: Sanaei, Kaveh | Plotner, Sydney | Oommen Jacob, Anson | Ramirez-Vick, Jaime | Vyavahare, Narendra | Nosoudi, Nasim

Article Type: Research Article

Abstract: BACKGROUND: The main objective of tissue engineering is to fabricate a tissue construct that mimics native tissue both biologically and mechanically. A recurring problem for tissue-engineered blood vessels (TEBV) is deficient elastogenesis from seeded smooth muscle cells. Elastin is an integral mechanical component in blood vessels, allowing elastic deformation and retraction in response to the shear and pulsatile forces of the cardiac system. OBJECTIVE: The goal of this research is to assess the effect of the vitamin A derivative all-trans retinoic acid (RA) and polyphenol pentagalloyl glucose (PGG) on the expression of elastin in human aortic smooth muscle …cells (hASMC). METHODS: A polycaprolactone (PCL) and the gelatin polymer composite was electrospun and doped with RA and PGG. The scaffolds were subsequently seeded with hASMCs and incubated for five weeks. The resulting tissue-engineered constructs were evaluated using qPCR and Fastin assay for their elastin expression and deposition. RESULTS: All treatments showed an increased elastin expression compared to the control, with PGG treatments showing a significant increase in gene expression and elastin deposition. Show more

Keywords: Elastogenesis, elastin, 1, 2, 3, 4, 6-pentagalloyl glucose (PGG), all-trans retinoic

DOI: 10.3233/BME-201152

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 3, pp. 145-157, 2021

Authors: Cheng, Olivia T. | Stein, Andrew P. | Babajanian, Eric | Hoppe, Kathryn R. | Li, Shawn | Jung, Hyungjin | Abrol, Anish | Akkus, Anna | Younesi, Mousa | Altawallbeh, Ghaith | Ghannoum, Mahmoud A. | Bonfield, Tracey | Akkus, Ozan | Zender, Chad A.

Article Type: Research Article

Abstract: BACKGROUND: Implantable medical devices and hardware are prolific in medicine, but hardware associated infections remain a major issue. OBJECTIVE: To develop and evaluate a novel, biologic antimicrobial coating for medical implants. METHODS: Electrochemically compacted collagen sheets with and without crosslinked heparin were synthesized per a protocol developed by our group. Sheets were incubated in antibiotic solution (gentamicin or moxifloxacin) overnight, and in vitro activity was assessed with five-day diffusion assays against Pseudomonas aeruginosa . Antibiotic release over time from gentamicin-infused sheets was determined using in vitro elution and high performance liquid chromatography (HPLC). …RESULTS: Collagen-heparin-antibiotic sheets demonstrated larger growth inhibition zones against P. aeruginosa compared to collagen-antibiotic alone sheets. This activity persisted for five days and was not impacted by rinsing sheets prior to evaluation. Rinsed collagen-antibiotic sheets did not produce any inhibition zones. Elution of gentamicin from collagen-heparin-gentamicin sheets was gradual and remained above the minimal inhibitory concentration for gentamicin-sensitive organisms for 29 days. Conversely, collagen-gentamicin sheets eluted their antibiotic load within 24 hours. Overall, heparin-associated sheets demonstrated larger inhibition zones against P. aeruginosa and prolonged elution profile via HPLC. CONCLUSION: We developed a novel, local antibiotic delivery system that could be used to coat medical implants/hardware in the future and reduce post-operative infections. Show more

Keywords: Local antibiotic delivery, electrochemically compacted collagen sheet, collagen sheet with heparin, Pseudomonas aeruginosa , implantable medical devices and hardware

DOI: 10.3233/BME-201133

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 3, pp. 159-170, 2021

Authors: Yokoi, Takuya | Uemura, Takuya | Takamatsu, Kiyohito | Shintani, Kosuke | Onode, Ema | Hama, Shunpei | Miyashima, Yusuke | Okada, Mitsuhiro | Nakamura, Hiroaki

Article Type: Research Article

Abstract: BACKGROUND: We previously demonstrated that a bioabsorbable nerve conduit coated with mouse induced pluripotent stem cell (iPSC)-derived neurospheres accelerated peripheral nerve regeneration in mice. OBJECTIVE: We examined the fate and utility of iPSC-derived neurospheres transplanted with nerve conduits for the treatment of sciatic nerve gaps in mice. METHODS: Complete 5-mm defects were created in sciatic nerves and reconstructed using nerve conduits that were either uncoated or coated with mouse iPSC-derived neurospheres. The survival of the neurospheres on the nerve conduits was tracked using an in vivo imaging. The localization of the transplanted cells and regenerating …axons was examined histologically. The gene expression levels in the nerve conduits were evaluated. RESULTS: The neurospheres survived for at least 14 days, peaking at 4--7 days after implantation. The grafted neurospheres remained as Schwann-like cells within the nerve conduits and migrated into the regenerated axons. The expression levels of ATF3, BDNF, and GDNF in the nerve conduit coated with neurospheres were upregulated. CONCLUSIONS: Mouse iPSC-derived neurospheres transplanted with nerve conduits for the treatment of sciatic nerve defects in mice migrated into regenerating axons, survived as Schwann-like cells, and promoted axonal growth with an elevation in the expression of nerve regeneration-associated trophic factors. Show more

Keywords: Induced pluripotent stem cells, nerve conduit, sciatic nerve, scaffold, regenerative medicine, neurospheres, neural stem/progenitor cells, cell viability, transcription factor, neurotrophic factor

DOI: 10.3233/BME-201182

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 3, pp. 171-181, 2021

Authors: Katsumi, Ryota | Sato, Takashi | Mochizuki, Tomoharu | Watanabe, Satoshi | Tanifuji, Osamu | Kawashima, Hiroyuki

Article Type: Research Article

Abstract: BACKGROUND: Assessment of three-dimensional (3D) femorotibial alignment is essential for successful knee osteoarthritis treatment in the elderly. The complex morphology of the posterior tibial slope (PTS) might have an influence on sagittal and rotational alignment and the positional relationship between the femur and tibia in the anterior–posterior (AP) direction under weight-bearing conditions. OBJECTIVE: This study aimed to clarify the association between the PTS and 3D femorotibial alignment under weight-bearing conditions in healthy Japanese elderly individuals. METHODS: We investigated the 3D femorotibial alignment of 110 lower extremities of 55 healthy individuals (26 women, 29 men, mean age: …70 ± 6 years). Using our previously reported 3D-to-2D image registration technique, we evaluated the 3D hip-knee-ankle angle (3DHKA) in the sagittal plane, rotational alignment, and the distance between the femoral and tibial origins in the AP direction (tibial AP position) as femorotibial alignment parameters under weight-bearing conditions. We assessed the medial and lateral PTS and their angular difference (PTS difference) as PTS parameters. Stepwise multiple linear regression analysis was performed using PTS parameters and other possible confounders (age, sex, height, and weight) as the independent variables and femorotibial alignment parameters as the dependent variable. RESULTS: Weight (𝛽 = 0.393, p < 0.001) and lateral PTS (𝛽 = 0.298, p < 0.001) were the predictors associated with 3DHKA in the sagittal plane. Lateral PTS (𝛽 = 0.304, p = 0.001) was the only predictor associated with the tibial AP position. Sex (𝛽 = −0.282, p = 0.002) and PTS difference (𝛽 = −0.231, p = 0.012) were associated with rotational alignment. CONCLUSIONS: We found that a steeper lateral PTS resulted in a more flexed knee and anterior tibia. The PTS difference was positively correlated with tibial external rotation. Our data could be used as the standard reference for realignment surgery to ensure PTS is appropriately maintained. Show more

Keywords: Posterior tibial slope, 3D, femorotibial alignment, weight-bearing conditions, healthy elderly

DOI: 10.3233/BME-201209

Citation: Bio-Medical Materials and Engineering, vol. 32, no. 3, pp. 183-194, 2021