Gene expression profiles of human adipose-derived mesenchymal stem cells dynamically seeded on clinically available processed nerve allografts and collagen nerve guides

It was hypothesized that mesenchymal stem cells(MSCs) could provide necessary trophic factors when seeded onto the surfaces of commonly used nerve graft substitutes. We aimed to determine the gene expression of MSCs when influenced by Avance■ Nerve Grafts or Neura Gen■ Nerve Guides. Human adipose-derived MSCs were cultured and dynamically seeded onto 30 Avance■ Nerve Grafts and 30 Neura Gen■ Nerve Guides for 12 hours. At six time points after seeding, quantitative polymerase chain reaction analyses were performed for five samples per group. Neurotrophic [nerve growth factor(NGF), glial cell line-derived neurotrophic factor(GDNF), pleiotrophin(PTN), growth associated protein 43(GAP43) and brain-derived neurotrophic factor(BDNF)], myelination [peripheral myelin protein 22(PMP22) and myelin protein zero(MPZ)], angiogenic [platelet endothelial cell adhesion molecule 1(PECAM1/CD31) and vascular endothelial cell growth factor alpha(VEGFA)], extracellular matrix(ECM) [collagen type alpha I(COL1A1), collagen type alpha III(COL3A1), Fibulin 1(FBLN1) and laminin subunit beta 2(LAMB2)] and cell surface marker cluster of differentiation 96(CD96) gene expression was quantified. Unseeded Avance■ Nerve Grafts and Neura Gen■ Nerve Guides were used to evaluate the baseline gene expression, and unseeded MSCs provided the baseline gene expression of MSCs. The interaction of MSCs with the Avance■ Nerve Grafts led to a short-term upregulation of neurotrophic(NGF, GDNF and BDNF), myelination(PMP22 and MPZ) and angiogenic genes(CD31 and VEGFA) and a long-term upregulation of BDNF, VEGFA and COL1A1. The interaction between MSCs and the Neura Gen■ Nerve Guide led to short term upregulation of neurotrophic(NGF, GDNF and BDNF) myelination(PMP22 and MPZ), angiogenic(CD31 and VEGFA), ECM(COL1A1) and cell surface(CD96) genes and long-term upregulation of neurotrophic(GDNF and BDNF), angiogenic(CD31 and VEGFA), ECM genes(COL1A1, COL3A1, and FBLN1) and cell surface(CD96) genes. Analysis demonstrated MSCs seeded onto Neura Gen■ Nerve Guides expressed significantly higher levels of neurotrophic(PTN), angiogenic(VEGFA) and ECM(COL3A1, FBLN1) genes in the long term period compared to MSCs seeded onto Avance■ Nerve Grafts. Overall, the interaction between human MSCs and both nerve graft substitutes resulted in a significant upregulation of the expression of numerous genes important for nerve regeneration over time. The in vitro interaction of MSCs with the Neura Gen■ Nerve Guide was more pronounced, particularly in the long term period(> 14 days after seeding). These results suggest that MSC-seeding has potential to be applied in a clinical setting, which needs to be confirmed in future in vitro and in vivo research.

THE INFLUENCE OF HETEROGENEOUS HABITATS ON THE GERMINATION OF ACANTHOPANAX SENTICOSUS SEEDS AND THE DYNAMICS OF ITS SEED POOL

Differences in germination of .A. Senticosus, an important shrub under the Korean Pine broad-leavd forest and its secondary forest in heterogeneous habitats and the dynamics of its seed pool have been studied by observations in location. The results showed that transformation rates from seeds to seedlings were in the following order : 16.8% in Larch plantations, 4. 1% in Mongolian oak forests, 2.7% in Birch forests, 1.8% in Korean Pine plantations, and 0.5% in hard wood forests.The life-span of seeds was determined to be four years in the simulating seed pool under Larch plantations. The percentage of the seedling output was, 14.5% in the 2nd year, 10. 1% in the 3rd year, and 1 .8% in the 4th year. Other types of the seed output were those f decayed 33. 1 %, senescent, 22.3%,predated by mice 14. 1%, which was variable due to the variation in the number of mouse, and only 1. 17% were eaten by insects and other soil animals.

Rainfall amount determines annual herb controls over soil seed bank and its similarity with vegetation in the Tengger Desert

Background:Soil seed banks may offer great potential for maintaining and restoring desert ecosystems that have been degraded by climate change and anthropogenic disturbance.However,few studies have explored the year‑to‑year dynamics in the species composition(richness and abundance)of these desert soil seed banks.Thus,we conducted a 4‑year study to assess the effects of environmental factors(meteorology and microtopography)and aboveground vegetation on the soil seed bank of the Tengger Desert,China.Results:We found the seed bank was dominated by annual herb species both in species richness and abundance.More rainfall in the growing season increased the number of seeds in the soil seed bank,and quadrat micro‑elevation had a negative effect on soil seed bank size.The species composition in the seed bank had significantly larger between‑year similarity than that in the aboveground vegetation due to the dominance of annual herb species.For different life forms,the species composition of annual herbs showed distinctly larger temporal similarity between the aboveground vegetation and the seed bank compared with perennial herbs and shrubs.Conclusions:Our findings highlight that the combined effects of environmental factors and plant life forms deter‑mine the species composition(especially the abundance)of soil seed banks in deserts.However,if degraded desert ecosystems are left to regenerate naturally,the lack of shrub and perennial herb seeds could crucially limit their restoration.Human intervention and management may have to be applied to enhance the seed abundance of perennial lifeforms in degraded deserts.