Human milk (HM) provides essential nutrients for infant growth and development. When own mother's milk is unavailable, donor human milk (DHM) is used and typically pasteurized, which may alter protein integrity. This study presents the use of external cavity-quantum cascade laser (EC-QCL) mid-infrared spectroscopy, as a rapid, non-destructive technique, to quantify both individual and total proteins in 276 HM and DHM samples. The method showed high accuracy (≥84% explained variance) and strong correlation with reference techniques. Pasteurization significantly reduced α-lactalbumin (24%) and lactoferrin (14%), while casein and total protein declined slightly (3%). Protein levels decreased notably during early lactation, then stabilized. In the cohort of the present study, no statistically significant differences in protein content were observed between preterm and term milk. EC-QCL spectroscopy also differentiated raw and pasteurized DHM. These results support EC-QCL as a reliable tool for clinical use and quality control, with implications for improving processing methods to preserve the nutritional and immunological integrity of DHM.

Background/Objectives: Post-thaw washing of cryopreserved hematopoietic progenitor cell (HPC) products is performed to remove dimethyl sulfoxide (DMSO) and reduce infusion-related toxicity. Hydroxyethyl starch (HES) has traditionally been used as an osmotic buffer in washing solutions; however, severe regulatory restrictions and market suspensions by the European Medicines Agency (EMA) have limited its availability in Europe. This pilot study evaluated the technical feasibility of utilizing a 4.0% human serum albumin (HSA)-based washing solution to replace HES without compromising post-thaw product quality parameters. Methods: Sixteen cryopreserved peripheral blood HPC bags from eight patients (cryopreserved between 2006 and 2015) were analyzed using a paired experimental design. For each patient, one bag was thawed and washed using the standard HES-HSA solution, while the paired bag was processed using an HSA-based solution. Total nucleated cell (TNC) recovery, TNC viability, viable CD34+ cell recovery, CD34+ viability, and clonogenic potential (CFU assay) were assessed immediately after washing and after 90 minutes of short-term post-thaw storage. Results: No statistically significant differences were observed between the HES-HSA and HSA washing solutions for any evaluated parameter. TNC recovery rates were 86.6 ± 6.6% and 88.9 ± 7.9% for the HES-HSA and HSA groups, respectively (p = 0.54). Post-thaw viability, viable CD34+ cell recovery, CD34+ viability, and clonogenic potential were stable and comparable between both processing strategies. Conclusions: An albumin-based washing solution provides cellular recovery, viability, and clonogenic performance comparable to conventional HES-containing formulations in a laboratory setting. Given current restrictions on HES due to clinical safety concerns, an albumin-based formulation represents a practical and logistically viable operational alternative for the post-thaw processing of peripheral blood HPC products.