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Stem cells are of widespread interest in regenerative medicine due to their capability of self-renewal and differentiation, which is regulated by their three-dimensional microenvironment. In this study, a computer-aided biofabrication technique based on laser-induced forward transfer (LIFT) is used to generate grafts consisting of mesenchymal stem cells (MSCs). We demonstrate that (i) laser printing does not cause any cell damage; (ii) laser-printed MSC grafts can be differentiated toward bone and cartilage; (iii) LIFT allows printing of cell densities high enough for the promotion of chondrogenesis; (iv) with LIFT three-dimensional scaffold-free autologous tissue grafts can be fabricated keeping their predefined structure, and (v) predifferentiated MSCs survived the complete printing procedure and kept their functionality. We believe that our results will find important applications in stem cell biology and tissue engineering.

While vitrified cryopreservation holds great promise, practical application has been limited to smaller systems (cells and thin tissues) due to diffusive heat and mass transfer limitations, which are typically manifested as devitrification and cracking failures during thaw. Here then we describe a new approach for rapidly and uniformly heating cryopreserved biospecimens with radiofrequency (RF) excited magnetic nanoparticles (mNPs). Importantly, heating rates can be increased several fold over conventional boundary heating techniques and are independent of sample size. Initial differential scanning calorimetry studies indicate that the addition of the mNPs has minimal impact on the freeze-thaw behavior of the cryoprotectant systems themselves. Then proof-of-principle experiments in aqueous and cryoprotectant solutions demonstrate the ability to heat at rates high enough to mitigate or eliminate devitrification (hundreds of °C/min) and scaled heat transfer modeling is used to illustrate the potential of this innovative approach. Finally, X-ray micro-computed-tomography (micro-CT) is investigated as a planning and quality control tool, where the density-based measurements are able to quantify changes in cryoprotectant concentration, mNP concentration, and the frozen state (i.e. crystallized versus vitrified).

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Human amniotic membrane (hAM) has been employed as scaffolding material in a wide range of tissue engineering applications, especially as a skin dressing and as a graft for corneal treatment, due to the structure of the extracellular matrix and excellent biological properties that enhance both wound healing and tissue regeneration. This review highlights recent work and current knowledge on the application of native hAM, and/or production of hAM-based tissue-engineered products to create scaffolds mimicking the structure of the native membrane to enhance the hAM performance. Moreover, an overview is presented on the available (cryo) preservation techniques for storage of native hAM and tissue-engineered products that are necessary to maintain biological functions such as angiogenesis, anti-inflammation, antifibrotic and antibacterial activity.