Tissue engineering, also called “regenerative medicine”, refers to attempt to create functional human tissue from cells in laboratory. This is a field that uses living cells, biocompatible materials, suitable biochemical and physical factors and their combinations, to create tissue-like structures.. To date, no tissue engineered skeletal muscle implants have been developed for clinical use, but it may represent a valid alternative to treat volumetric muscle loss in the near future. Herein, we reviewed the literature and showed different techniques to produce synthetic tissues with the same architectural, structural and functional properties of native tissues.

Background Very few cases of Pneumocystis jirovecii pneumonia (PCP) have been reported in COVID-19 so far, mostly in patients with concomitant HIV infection or in solid organ transplant recipients. Despite COVID-19 is associated with lymphopenia and use of steroids, there are no studies specifically aimed to investigate risk factors for PCP in COVID-19 Methods retrospective case-control study in a cohort of patients with confirmed COVID-19. Direct immunofluorescence assay on respiratory samples was used to diagnose PCP. Results We enrolled 54 patients. Patients with PCP had significant lower median lymphocyte values (p=0.033), longer COVID-19 disease duration (p=0.014), higher cumulative dose of steroid received (p=0.026), higher CRP values (p=0.005) and lower SARS-CoV-2 vaccination rate than controls (p=0.029). Cumulative steroid dose (p=0.042) and the highest CRP value during the stay (p=0.012) were identified as risk factor for PCP, while SARS-CoV-2 vaccination with one (p=0.029) and two doses (p=0.049) as a protective factor for PCP, although not independently associated. Conclusions PCP develops in COVID-19 patients regardless of immunosuppressive conditions. However, a higher rate of PCP is significantly associated with the cumulative steroidal dose, high CRP values and lack of vaccination.