The key to proper implant integration in bone replacement is to orchestrate the complex interactions between materials and tissues. Moreover, due to the rapid demographic shift towards aging societies and the increase in elderly and osteoporotic patients, it is of great importance that implant materials are osteointegrative in not only healthy but also compromised bone tissues. Here, titanium (Ti) scaffolds were subjected to shifted laser surface texturing (sLST) using a nanosecond pulsed laser to create an open pore macrotopography with micro-and nano-Ti droplets. In contrast to conventional laser texturing, which leads to high heat accumulation; in sLST, the frequency of laser pulses is low, allowing for resolidification, thereby creating a surface with abundant coverage micro-/nanodroplets. The main objective was to compare the cellular responses of human mesenchymal stromal cells (hMSCs) on sLST-textured Ti surfaces (LT-Ti) for the first time with standard sand-blasted, acid-etched surfaces (SLA-Ti). In-depth analyses of cell survival, proliferation, shape, mineralization, and gene expression were performed. Cell survival/proliferation was found to be similar on both surfaces; however, SEM imaging revealed differences in hMSC morphology. On LT-Ti, cells adopted well-rounded shapes, whereas on SLA-Ti they assumed more planar shapes. Bulk RNA sequencing performed after short-term culture on both surfaces disclosed expression changes in genes such as DUSP6, TNFSF12-TNFSF13 and SULT1A4. Remarkably, the osteogenic differentiation capacity of hMSCs was significantly enhanced on LT-Ti compared to SLA-Ti. Furthermore, aged/osteoporotic donor cohorts showed significantly enhanced matrix mineralization on LT-Ti. In conclusion, our novel results demonstrate that sLST-Ti surfaces are safe, highly biocompatible, can rescue patient-cohort-specific mineralization behavior, and therefore hold great potential for the development into next-generation implants, which are suitable for both the elderly and bone-compromised populations.

The goal was to analyze the cellular response, specifically the osteogenic capacity, of titanium (Ti) implants harbouring a novel laserbased-surface-structure with the overall aim: augmented osteointegration. Surface micro-/nanoproperties greatly influence cell behaviour at the tissue-implant-interface and subsequent osteointegration. We investigated Ti-materials subjected to a specially developed shifted-Laser-Surface-Texturing (sLST) technology and compared them to a standard roughening-technique (sand-blasting-acid-etching, SLA). The biological response was evaluated with hMSCs, which are naturally available at the bone-implant-interface. We hypothesized: the novel surface is beneficial for our three different (young/healthy-YH; aged/healthy-AH;aged/osteoporotic-OP) cohorts.The sLST was performed using a SPI-G3-series laser (beam-wavelength=1064nm, pulse-duration=200ns). For the SLA surface, Ti was sandblasted, afterwards acid-etched (HCl/H2SO4). Three different hMSC cohorts were studied: YH: n=6,29±6; AH: n=5,79±5; OP: n=5,76±5 years (osteoporosis confirmed via DEXA-scan). OP hMSCs show e.g. ColI-deficient-matrix and decreased mineralization. Cells were examined for survival, cell proliferation and cytoskeleton arrangement. Osteogenic differentiation was carried out over 21 days, matrix mineralization was validated with Alizarin-Red-S-staining and quantification.Laser-texturing generated precisely the desired microgeometry. On nanostructural level, differently-sized Ti-droplets were formed stochastically by laser-induced-Ti-plasma. Live/dead-/Actin-stainings showed comparable results for all cohorts and surfaces in terms of survival and cell shape. On Ti-materials, cell growth showed no significant difference between the 3 cohorts. Alizarin quantification revealed the highest levels on laser-textured-surfaces; highest value for YH, followed by AH, lastly OP; no significance between AH/YH, but between OP/YH (p<0.0001). However, mineralization of all cohorts cultured on laser-textured-surfaces increased significantly (p20fold higher value in the OP-cohort (AH:11fold, YH:6fold).The data proves the biocompatibility of the laser-structured-Ti for young+aged cohorts. Osteogenic differentiation was significantly augmented on laser-treated-Ti. Most intriguingly, OP-donors could reach manifold increased mineralization, suggesting the novel laser texturing can counteract the osteoporotic phenotype. As osteogenesis-enhancing capacities may be related to mechanisms controlling cellular shape/fate, further investigations referring to this are currently ongoing. In conclusion, our laser-textured-Ti-materials are safe, can have a demand-oriented designer-surface-topography and represent a great potential for development into next-generation-implants suitable for different patient-cohorts, especially osteoporosis patients.