Table 3.

The designed conceptual framework

Sections	Features	Details
Material	Material	Type of support material for tissue regeneration exploited in the described experiment.
	Material group	Cluster of biomaterials the selected one belongs to: metals, polymers, ceramics, gels, composites, or other.
	Features	Morphological and chemico-physical characteristics of the material: bulk properties (total porosity, pore shape and size, pore size distribution, pores volume, pore interconnection); surface properties (chemical/physical functionalization); scaffold properties (sample size and shape [optional]); mechanical properties (such as Bulk modulus and maximum strain) [optional]; chemico-physical properties (such as resorbability and thermoplasticity) [optional].
Cell	Cells type	Type of cells seeded on the biomaterial, both specifying: the type of cells (for example fibroblasts, osteoblasts, chondrocytes); if they are cell lines (reporting the specific cell line code) or primary cells; in this case, the related extraction protocol.
	Donor organism	Species of organism the cells derive from.
	Donor features	Age, gender, weight and health status of the donor.
In vitro experiment	Cell expansion phase	Time or number of expansions (passages) the cells underwent in plate before being seeded in the biomaterial; type of culture medium used during cell expansion; list of the growth factors that have been added to the cell expansion; for each growth factor, the concentration (mg/ml or Mol) must be reported, together with its isoform, if it exists (as in the case of the Transforming Growth Factor-beta isoforms, which play critical roles in growth regulation and development), and the organism species the growth factor comes from.
	Cell culture phase onto the biomaterial	Number (cell quantity) or concentration (number of cells per unit of volume) of cells seeded in the biomaterial; cell seeding efficiency; type of culture medium used during cell culture onto the material; cell culture time; list of the growth factors that have been added to the cell culture onto the biomaterial; for each growth factor, the concentration (mg/ml or Mol) must be reported, together with its isoform, if it exists (as in the case of the Transforming Growth Factor-beta isoforms, which play critical roles in growth regulation and development), and the organism species the growth factor comes from.
	Cell characterization	Phenotypic/genotypic characterization of cells before their seeding onto biomaterials: evaluation of the expression of cell surface markers through flow cytometry analysis. [optional]
In vivo experiment	Host features	Species of the host, age [optional], gender, weight and health status of the host.
	Implant features	Orthotopic (implant placed in the original, correct site) or ectopic (implant inserted under skin); time the biomaterial remains within the animal model; dimension of the implanted samples [optional]; surgical procedure for the implant.
Results	In vitro matrix deposition	Evaluation and report of the matrix deposition in in vitro experiments, through morphology, mechanical, biomolecular and biochemical tests (see tests listed below), to obtain a qualitative and quantitative evaluation of scaffold performances. All the results have to be reported specifying the technique used, the applied protocol, the value and measurement unit of the result (in case of quantitative analysis) or the discussion of the result (in case of qualitative analysis).
	In vivo tissue generation	Evaluation and report of the growth of tissue in in vivo experiments, through morphology, mechanical, biomolecular and biochemical tests (see tests listed below), to obtain a qualitative and quantitative evaluation of scaffold performances. All the results have to be reported specifying the technique used, the applied protocol, the value and measurement unit of the result (in case of quantitative analysis) or the discussion of the result (in case of qualitative analysis).
	Biomaterial degradation/resorption	Kinetics, amount or percentage of biomaterial degradation/resorption over time, either in vitro or in vivo [optional].
	Adverse effects	Eventual biomaterial toxicity, evaluated either in vitro (reporting cytotoxicity tests) or in vivo (such as inflammatory response, foreign body reaction, release of degradation by-products)
Tissue/matrix characterization	Morphology tests	Results of histological and microscopy tests (i.e. SEM, TEM) used to study structures of the generated tissue/matrix (at level of tissue and cell).
	Mechanical tests	Values of main indexes (such as Young module) to define mechanical goodness of the generated tissue/matrix.
	Biomolecular tests	Genes and proteins level within tissue/matrix cells. Used technique (typically real time RT-PCR or immunohistochemistry; recently high-throughput technologies such as gene expression microarray were introduced). Examples of bone and cartilage markers are type I collagen, RUNX2 protein, osteonectin, osteopontin, osteocalcin, SOX9.
	Biochemical tests	Amount of calcium and mineralization (for bone), amount of aggrecan and glycosaminoglycan (for cartilage); the exploited technique.

Features are grouped by 'concepts', and detailed listing mandatory and non-compulsory (flagged as [optional]) aspects to be reported for describing a bone/cartilage experiment.