Correction to: Mesenchymal Stem Cell Deformability and Implications for Microvascular Sequestration.

This article was updated to correct the spelling of author Brittany L. Banik's name.

Mesenchymal Stem Cell Deformability and Implications for Microvascular Sequestration.

Mesenchymal stem cells (MSCs) have received considerable attention in regenerative medicine, particularly in light of prospects for targeted delivery by intra-arterial injection. However, little is known about the mechanics of MSC sequestration in the microvasculature and the yield pressure (PY), above which MSCs will pass through microvessels of a given diameter. The objectives of the current study were to delineate the dependency of PY on cell size and the heterogeneity of cell mechanical properties and diameters (DCELL) of cultured MSCs. To this end the transient filtration test was employed to elucidate the mean filtration pressure (〈PY〉) for an ensemble of pores of a given size (DPORE) similar to in vivo microvessels. Cultured MSCs had a log-normal distribution of cell diameters (DCELL) with a mean of 15.8 ± 0.73 SD µm. MSC clearance from track-etched polycarbonate filters was studied for pore diameters of 7.3-15.4 µm. The pressure required to clear cells from filters with 30-85 × 103 pores rose exponentially with the ratio λ = DCELL/DPORE for 1.1 ≤ λ ≤ 2.2. The clearance of cells from each filter was characterized by a log-normal distribution in PY, with a mean filtration pressure of 0.02 ≤ ã€ˆPY〉 ≤ 6.7 cmH2O. For λ ≤ 1.56, the yield pressure (PY) was well represented by the cortical shell model of a cell with a viscous interior encapsulated by a shell under cortical tension τ0 = 0.99 ± 0.42 SD dyn/cm. For λ > 1.56, the 〈PY〉 characteristic of the cell population rose exponentially with λ. Analysis of the mean filtration pressure (〈PY〉) of each sample suggested that the larger diameter cells that skewed the distribution of DCELL contributed to about 20% of the mean filtration pressure. Further, if all cells had the same deformability (i.e., PY as a function of λ) as the average cell population, then ã€ˆPY〉 would have risen an order of magnitude above the average from fivefold at λ = 1.56 to 200-fold at λ = 2.1. Comparison of ã€ˆPY〉 to published microvascular pressures suggested that ã€ˆPY〉 may exceed microvessel pressure drops for λ exceeding 2.1, and rise 14-fold above capillary pressure drop at λ = 3 leading to 100% sequestration. However, due to the large variance of in vivo microvascular pressures entrapment of MSCs may be mitigated. Thus it is suggested that selecting fractions of the MSC population according to cell deformability may permit optimization of entrapment at sites targeted for tissue regeneration.

Structural properties of starch-chitosan-gelatin foams and the impact of gelatin on MC3T3 mouse osteoblast cell viability.

BACKGROUND: This study examines the effects of adding gelatin to a starch-chitosan composite foam, focusing on the altered structural and biological properties. The compressive modulus of foams containing different gelatin concentrations was tested in dry, wet, and lyophilized states. MC3T3 mouse osteoblast cells were used to test the composite's ability to support cell growth. The stability of the foams in α-MEM culture media with and without cells was also examined. RESULTS: It was found that for dry foams, the compressive modulus increased with increasing gelatin content. For foams tested in wet and lyophilized states, the compressive modulus peaked at a gelatin concentration of 2.5% and 5%, respectively. The growth of MC3T3 mouse osteoblast cells was tested on the foams with different gelatin concentrations. The addition of gelatin had a positive effect on the cell growth and proliferation. CONCLUSION: The composite foam containing gelatin improved cell growth and is only dissolved by the growing cells at a rate influenced by the initial concentration of gelatin added to the foam.

Human Mesenchymal Stem Cell Morphology and Migration on Microtextured Titanium.

The implant used in spinal fusion procedures is an essential component to achieving successful arthrodesis. At the cellular level, the implant impacts healing and fusion through a series of steps: first, mesenchymal stem cells (MSCs) need to adhere and proliferate to cover the implant; second, the MSCs must differentiate into osteoblasts; third, the osteoid matrix produced by the osteoblasts needs to generate new bone tissue, thoroughly integrating the implant with the vertebrate above and below. Previous research has demonstrated that microtextured titanium is advantageous over smooth titanium and PEEK implants for both promoting osteogenic differentiation and integrating with host bone tissue; however, no investigation to date has examined the early morphology and migration of MSCs on these surfaces. This study details cell spreading and morphology changes over 24 h, rate and directionality of migration 6-18 h post-seeding, differentiation markers at 10 days, and the long-term morphology of MSCs at 7 days, on microtextured, acid-etched titanium (endoskeleton), smooth titanium, and smooth PEEK surfaces. The results demonstrate that in all metrics, the two titanium surfaces outperformed the PEEK surface. Furthermore, the rough acid-etched titanium surface presented the most favorable overall results, demonstrating the random migration needed to efficiently cover a surface in addition to morphologies consistent with osteoblasts and preosteoblasts.

Multiscale Poly-(ϵ-caprolactone) Scaffold Mimicking Nonlinearity in Tendon Tissue Mechanics.

Regenerative medicine plays a critical role in the future of medicine. However, challenges remain to balance stem cells, biomaterial scaffolds, and biochemical factors to create successful and effective scaffold designs. This project analyzes scaffold architecture with respect to mechanical capability and preliminary mesenchymal stem cell response for tendon regeneration. An electrospun fiber scaffold with tailorable properties based on a "Chinese-fingertrap" design is presented. The unique criss-crossed fiber structures demonstrate non-linear mechanical response similar to that observed in native tendon. Mechanical testing revealed that optimizing the fiber orientation resulted in the characteristic "S"-shaped curve, demonstrating a toe region and linear elastic region. This project has promising research potential across various disciplines: vascular engineering, nerve regeneration, and ligament and tendon tissue engineering.

Polymeric nanoparticles: the future of nanomedicine.

Polymeric nanoparticles (NPs) are one of the most studied organic strategies for nanomedicine. Intense interest lies in the potential of polymeric NPs to revolutionize modern medicine. To determine the ideal nanosystem for more effective and distinctly targeted delivery of therapeutic applications, particle size, morphology, material choice, and processing techniques are all research areas of interest. Utilizations of polymeric NPs include drug delivery techniques such as conjugation and entrapment of drugs, prodrugs, stimuli-responsive systems, imaging modalities, and theranostics. Cancer, neurodegenerative disorders, and cardiovascular diseases are fields impacted by NP technologies that push scientific boundaries to the leading edge of transformative advances for nanomedicine.